Bretylium compositions and kits and their use in preventing and treating cardiovascular conditions

ABSTRACT

The present invention is directed to novel pharmaceutical combinations including compositions and kits comprising bretylium as the active ingredient, as well as methods for preventing and/or treating conditions related to the cardiovascular system using such novel pharmaceutical combinations.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from U.S. Provisional Application Ser. No. 60/394,953, filed Jul. 10, 2002, and U.S. Provisional Application Ser. No. 60/329,447, filed Oct. 15, 2001, and as a continuation-in-part of U.S. patent application Ser. No. 09/869,940 (now U.S. Pat. No. 6,482,811), filed Nov. 27, 2001, which is a 371 U.S. National Application of PCT/US00/00350, filed Jan. 6, 2000, which claims the benefit of U.S. Provisional Application Ser. No. 60/116,567, filed Jan. 21, 1999 and U.S. Provisional Application Ser. No. 60/115,143, filed Jan. 8, 1999. The entire texts of U.S. Provisional Application Ser. No. 60/394,953, U.S. Provisional Application Ser. No. 60/329,447, U.S. patent application Ser. No. 09/869,940, International Application PCT/US00/00350, U.S. Provisional Application Ser. No. 60/116,567 and U.S. Provisional Application Ser. No. 60/115,143 are hereby incorporated herein by reference in their entirety.

FIELD OF THE INVENTION

This invention relates to novel compositions and kits comprising a pharmaceutically active quaternary ammonium cation such as bretylium and a facilitating anion with or without other active agents such as, for example, a β-receptor blocker. This invention also relates to the use of such compositions and kits to prevent and/or treat various cardiovascular conditions.

BACKGROUND OF THE INVENTION

A variety of quaternary ammonium salts are pharmaceutically active.

Bretylium tosylate 1 (also known as 2-bromobenzylethyldimethylammonium p-toluenesulfonate) has the structure:

It is a known Class III antiarrhythmic agent and an adrenergic blocking agent. The bretylium cation of this compound is reported to directly modify the electrical properties of the myocardium. It also is reported to depress adrenergic neural transmission by blocking neuronal norepinephrine release and re-uptake. Bretylium tosylate consequently has been used worldwide to suppress life-threatening ventricular tachyarrhythmias, such as ventricular tachycardia and fibrillation. Bacaner (in U.S. Reissue Pat. No. 29,618, incorporated herein by reference) discloses suppressing cardiac ventricular fibrillation and cardiac arrhythmias generally by administering bretylium tosylate. Similarly, Bacaner (in U.S. Pat. No. 3,911,125, incorporated herein by reference) discloses treating angina pectoris, treating coronary insufficiency, and preventing myocardial infarction by administering bretylium tosylate and bethanidine sulfate.

Bretylium is the only known drug that can induce the phenomenon of spontaneous defibrillation in large hearts (dog and man). In dogs treated with bretylium, electrically induced ventricular fibrillation by superthreshold shocks persisting for as long as two minutes is often not sustained because spontaneous defibrillation to sinus rhythm occurs repeatedly. Non-sustained ventricular fibrillation has also been observed in bretylium-treated dogs and humans subjected to coronary artery legation. This phenomenon has also been reported in patients receiving bretylium treatment.

Unformulated bretylium tosylate exhibits poor and unpredictable absorption into the bloodstream when orally ingested. Thus, oral administration of bretylium tosylate alone is generally unsuitable for treating heart conditions and has not been approved by the FDA because of poor and unpredictable tablet absorption. Accordingly, bretylium tosylate is instead usually administered parenterally in the form of an injectable solution. This mode of administration, however, is inconvenient and painful, particularly for chronic administration, and slow in onset of therapeutic action because bretylium tosylate has poor lipid solubility and difficulty crossing capillary and heart membranes.

Administration of bretylium tosylate (or other quaternary ammonium compounds) may also result in severely reduced ambulation in a recipient due to a sharp drop in blood pressure on assuming the upright position, resulting in dizziness and loss of consciousness. The severity of this side-effect, however, can be reduced (and the therapeutic effects of the bretylium cation can be enhanced) by administering a tricyclic anti-depressant agent (e.g., protriptyline, mazindol, amitriptyline, nortriptyline, or desipramine) with the bretylium tosylate, as disclosed by Bacaner in U.S. Pat. No. 5,036,106.

A number of studies on the bioavailability of bretylium tosylate have been described in the literature. Most of these studies, however, have primarily focused on parenteral, rectal, and other non-ingested compositions comprising bretylium tosylate. Most also involve the administration of bretylium tosylate compositions under alkaline conditions.

Neubert et al. (in Ion Pair Approach of Bretylium, Pharm. Ind. 54, Nr. 4 (1992)) disclose a series of experiments in which bretylium tosylate was studied in the presence of saccharin, dodecylsulfate, or hexylsalicylate anions. The partition coefficient for the bretylium ion in the presence of these anions was measured using an alkaline (pH=7.2) n-octanol/buffer system and using an alkaline (pH=7.2) absorption model system employing an artificial lipid membrane. Bretylium absorption in vivo was also measured in rabbits receiving the bretylium tosylate in combination with these anions by i.v. injection (an i.v. injection of bretylium tosylate in Sorensen phosphate buffer (pH=7.2), together with an i.v. injection of hexylsalicylic acid in ethanol/Sorensen phosphate buffer (pH=7.2)) or rectal administration.

Neubert et al. (in Influence of Lipophilic Counter Ions on the Transport of Ionizable Hydrophilic Drugs, J. Pharm. Pharmacol. 1991, 43: 204-206) disclose a series of experiments on the influence of the counterions hydroxynaphthoate, naphthylsulphonate, adamantoate, desoxycholate, dehydrocholate, octanoate, decanoate, dodecanoate, hexadecanoate, and hexylsalicylate on the transport of bretylium using an alkaline (pH=7.2) absorption model system. It was reported that the use of hydroxynaphthoate, adamantoate, desoxycholate, or dehydrocholate counterions resulted in minimal or no increase in bretylium transport across the membrane. No therapeutic or electrophysiologic action is disclosed.

Neubert et al. (in Drug Permeation Through Artificial Lipoid Membranes, Pharmazie 42 (1987), H. 5) evaluated the effect of alkylated derivatives of salicylic acid, particularly hexylsalicylic acid, on the partition and transport of ionized basic drugs including bretylium tosylate using lipophilic membranes in alkaline (pH=7.2) lipoid membrane models.

Hartl et al. (in Influence of the Ion-Pair-Formation of Bretylium and Hexylsalicylic Acid on Their Influence on Blood Plasma Levels in Dogs, Pharmazie 45 (1990), H. 4) report an improvement in biological bretylium levels in dog plasma when a bretylium-tosylate/hexylsalicylic acid combination was administered to dogs by i.v. injection (an i.v. injection of bretylium tosylate in Sorensen phosphate buffer (pH=7.2), together with an i.v. injection of hexylsalicylic acid in ethanol/Sorensen phosphate buffer (pH=7.2)). Hartl et al., however, do not discuss how to improve the bretylium level in the myocardium of the heart or the therapeutic effects of doing so or inducing sympathetic blockade.

Neubert et al. (in Influence of the Ion-Pair-Formation on the Pharmacokinetic Properties of Drugs (Part 4), Pharmazie 43 (1988), H. 12) report a series of experiments to determine the pharmacokinetic parameters of bretylium tosylate administered in combination with hexylsalicylic acid in rabbits by i.v. injection or rectally. No therapeutic or electrophysiologic action is disclosed, nor is there any reference to oral administration.

Amlacher et al. (in Influence of Ion-Pair Formation on the Pharmacokinetic Properties of Drugs, J. Pharm. Pharmacol. 1991, 43: 794-797) disclose a series of experiments to measure the partition coefficients for the bretylium ion in the presence of salicylic acid using an alkaline (pH=7.2) n-octanol/buffer system. Bretylium absorption in vivo was also measured in rabbits receiving an i.v. injection of bretylium tosylate in Sorensen phosphate buffer (pH=7.2), together with an i.v. injection of hexylsalicylic acid in ethanol/Sorensen phosphate buffer (pH=7.2).

Neubert et al. (in Influence of the Ion-Pair-Formation on the Pharmacokinetic Properties of Drugs (Part 5), Pharmazie 44 (1989), H. 9) disclose a series of experiments on the effect of ion-pair formation on the elimination of bretylium and hexylsalicylic acid in rats. In these experiments, the rats received an i.v. injection of bretylium tosylate in Sorensen phosphate buffer (pH=7.2), together with an i.v. injection of hexylsalicylic acid in ethanol/Sorensen phosphate buffer (pH=7.2) and, in some instances, an oral dose of cholestyramine. Neubert et al. concluded that the pharmacokinetic parameters of bretylium were not influenced by hexylsalicylic acid.

Cho (in WO 87/05505) discloses compositions comprising particles consisting essentially of a solid emulsifying agent and a surfactant, a biologically active proteinaceous material bound to the surface of the particles, and a lipid coating surrounding such particles. While Cho is primarily directed to pharmaceutical compositions comprising insulin, he does state generally that other pharmaceutical agents, such as bretylium tosylate, could be employed. Additional ingredients in the composition are described to include, among others, sodium lauryl sulfate (as a surfactant), sodium bicarbonate, and citric acid.

Stanley et al. (in U.S. Pat. Nos. 5,288,497 and 5,288,498) disclose a dissolvable or non-dissolvable drug containing matrix form for administering a drug for absorption through the mucosal tissues of the mouth, pharynx, and esophagus. Stanley et al. identify a large group of active drugs that can be administered buccally in accordance with the invention. These references further disclose a variety of additional ingredients that can be included in the matrix including, among others, sodium lauryl sulfate and sodium dodecyl sulfate (as “permeation enhancers”) and buffering systems (to adjust salival pH). Although the Stanley references list bretylium tosylate as one of the drugs that can be administered in this manner, bretylium tosylate is very bitter and too unpalatable for human consumption by this mode of administration.

Finally, Bacaner et al. (in “Synergistic Action of Bretylium With Low Doses Of Propranolol Renders The Canine Heart Virtually Invulnerable To Sustained Ventricular Fibrillation”, Circulation, Supp. IV, page 111 (1987)) disclose a synergistic enhancement in the onset and magnitude of the anti-fibrillatory action caused by bretylium tosylate when a small, non-β-blocking dosage of propranolol is added to a bretylium tosylate bolus injected into dogs. This synergism also has been demonstrated with other β-blocking drugs (sotalol, esmolol, metoprolol and carvedilol).

SUMMARY OF THE INVENTION

This invention provides, in part, novel pharmaceutical compositions and kits which may be administered to prevent and/or treat medical conditions related to the cardiovascular system. These compositions and kits have been found to be particularly suitable for oral administration, although they also have been found to be generally useful when administered parenterally. In addition, they often tend to exhibit superior activity, time for onset of action, potency, safety, and/or therapeutic effectiveness relative to conventionally used quaternary ammonium formulations (particularly previously-tried oral formulations such as bretylium tosylate). In many instances, the compositions and kits of this invention are especially advantageous because they may be self-administered as needed (for example, at a person's residence or place of work to prevent sudden cardiac death and/or non-fatal myocardial infarction) without the assistance of a health care professional. As defined herein, the term “composition” refers to a single compound or a mixture of compounds. A “kit,” in contrast, refers collectively to therapeutic ingredients which are in the form of at least two separate, discrete sources that are independently administered (whether jointly or at different times).

Briefly, therefore, this invention is directed to a pharmaceutical combination useful for preventing and/or treating a cardiovascular condition. The pharmaceutical combination comprises a bretylium cation or a source of a bretylium cation; an acetylsalicylate anion or a source of an acetylsalicylate anion; and a β-receptor blocker or a source of a β-receptor blocker. The combination is further characterized in that the acetylsalicylate anion comprises a compound of the structure:

-   -   wherein R¹⁷ is independently hydrocarbyl or substituted         hydrocarbyl and R¹⁸ is hydrogen, hydrocarbyl or substituted         hydrocarbyl. Further, the bretylium cation or the source of the         bretylium cation, the acetylsalicylate anion or the source of         the acetylsalicylate anion, and the β-receptor blocker or the         source of the β-receptor blocker together are present in the         pharmaceutical combination in a therapeutically effective         amount.

In a preferred embodiment, the pharmaceutical combination comprises comprises a pharmaceutical composition comprising a bretylium cation, an acetylsalicylate anion and a β-receptor blocker. The acetylsalicylate anion of the composition comprises a compound of the structure:

-   -   wherein R¹⁷ is independently hydrocarbyl or substituted         hydrocarbyl and R¹⁸ is hydrogen, hydrocarbyl or substituted         hydrocarbyl. Further, the bretylium cation, the acetylsalicylate         anion and the β-receptor blocker together are present in the         pharmaceutical composition in a therapeutically effective         amount.

In another preferred embodiment, the pharmaceutical combination comprises a pharmaceutical kit comprising a source of a bretylium cation, a source of a β-receptor blocker, and a source of an acetylsalicylate anion. The acetylsalicylate anion of the pharmaceutical kit comprises a compound of the structure:

-   -   wherein R¹⁷ is independently hydrocarbyl or substituted         hydrocarbyl and R¹⁸ is hydrogen, hydrocarbyl or substituted         hydrocarbyl. The kit is further characterized in that the         bretylium cation, the β-receptor blocker and the         acetylsalicylate anion are present in the pharmaceutical kit in         a therapeutically effective amount (i.e., the bretylium cation,         the β-receptor blocker and the acetylsalicylate anion are         present in the kit in amounts such that their combination is         therapeutically effective after the components of the kit are         administered).

The present invention is further directed to a pharmaceutical combination useful for preventing and/or treating a cardiovascular condition. The pharmaceutical combination comprises a bretylium cation or a source of a bretylium cation; acetylsalicylic acid or an alkali metal salt of acetylsalicylic acid; and

-   -   a β-receptor blocker or a source of a β-receptor blocker. The         pharmaceutical combination is characterized in that the         pharmaceutical combination is suitable for oral ingestion; and         the bretylium cation or the source of a bretylium cation, the         acetylsalicylic acid or the alkali metal salt of acetylsalicylic         acid, and the β-receptor blocker or the source of a β-receptor         blocker together are present in the pharmaceutical combination         in a therapeutically effective amount.

In a preferred embodiment, the pharmaceutical combination comprises a pharmaceutical composition comprising a bretylium cation, acetylsalicylic acid or an alkali metal salt of acetylsalicylic acid and a β-receptor blocker. The pharmaceutical composition is suitable for oral ingestion and further characterized in that the bretylium cation, the acetylsalicylic acid or alkali metal salt of acetylsalicylic acid and the β-receptor blocker together are present in the pharmaceutical composition in a therapeutically effective amount.

In another preferred embodiment, the pharmaceutical combination comprises a pharmaceutical kit comprising a source of a bretylium cation, acetylsalicylic acid or an alkali metal salt of acetylsalicylic acid and a source of a β-receptor blocker. The source of the bretylium cation, the source of the acetylsalicylate anion and the source of the β-receptor blocker are, in combination, suitable for oral ingestion. The kit is further characterized in that the bretylium cation, the acetylsalicylic acid or alkali metal salt of acetylsalicylic acid and the β-receptor blocker are present in the kit in a therapeutically effective amount.

The present invention is further directed to a pharmaceutical composition comprising from about 10% to about 40% by weight bretylium cation, from about 5% to about 40% by weight acetylsalicylate anion, and from about 0.1% to about 1.0% by weight β-receptor blocker. In a preferred embodiment, the β-receptor blocker of the pharmaceutical composition comprises propranolol. In another preferred embodiment, the β-receptor blocker of the pharmaceutical composition comprises metoprolol. In still another preferred embodiment, the pharmaceutical composition further comprises from about 30% to about 75% by weight neutralizing agent, preferably a mono-, di-, or poly-amino sugar such as methyl glucamine.

Still further, the present invention is directed to a pharmaceutical composition comprising a bretylium cation, an acetylsalicylate anion, a β-receptor blocker and a neutralizing agent. In a preferred embodiment, the β-receptor blocker of the pharmaceutical composition comprises propranolol. In another preferred embodiment, the β-receptor blocker of the pharmaceutical composition comprises metoprolol. Preferably, the composition is in a form comprising a solution or a suspension, more preferably in a form suitable for administration as an emergency resuscitation solution for treating sudden cardiac arrest.

Still further, the present invention is directed to a method for treating sudden cardiac arrest in a human or animal patient. The method comprises administering a pharmaceutical composition comprising a bretylium cation, an acetylsalicylate anion, a β-receptor blocker and a neutralizing agent to a subject in need thereof. In a preferred embodiment, the pharmaceutical composition comprises a bretylium cation, an acetylsalicylate anion, propranolol and methyl glucamine. In another preferred embodiment, the pharmaceutical composition comprises a bretylium cation, an acetylsalicylate anion, metoprolol and methyl glucamine.

Still further, the present invention is directed to a method for preventing and/or treating a cardiovascular condition. The method comprises administering a pharmaceutical combination of the present invention to a subject in need thereof. More particularly, the pharmaceutical combinations of the present invention can be administered to: (1) prevent sudden cardiac death; (2) prevent and/or treat myocardial infarction; (3) prevent and/or treat congestive heart failure; (4) prevent and/or treat ventricular fibrillation; (5) prevent and/or treat ventricular arrhythmia; (6) prevent and/or treat ventricular tachycardia; (7) prevent and/or treat ventricular premature heartbeats; (8) prevent and/or treat atrioventricular dissociation; (9) prevent and/or treat multifocal ectopic beats; (10) prevent and/or treat premature ventricular extrasystoles; (11) prevent and/or treat bigeminal rhythm; (12) prevent and/or treat trigeminal rhythm; (13) prevent and/or treat angina pectoris; (14) prevent and/or treat coronary insufficiency; (15) prevent and/or treat sympathetically induced pain; (16) restore and/or maintain normal sinus rhythm; (17) increase the effective ventricular refractory period; (18) increase the sinus automaticity transiently; (19) prolong the Purkinje action potential duration; (20) induce post-ganglionic sympathetic blockade; (21) block the sympathetic nervous system; (22) reduce vascular impedance; (23) increase the ventricular fibrillation threshold; (24) prolong the action potential duration of cardiac cells; and/or (25) prevent or treat congestive heart failure or coronary spasm.

The present invention is further directed to a method for preventing and/or treating atrial fibrillation. The method comprises administering an anti-fibrillation pharmaceutical composition to a patient susceptible to atrial fibrillation wherein the composition comprises a salt of bretylium, acetylsalicylic acid or an alkali metal salt of acetylsalicylic acid and a β-receptor blocker. In a preferred embodiment, the anti-fibrillation composition comprises a salt of bretylium, acetylsalicylic acid or an alkali metal salt thereof and propranolol or metoprolol.

The present invention is still further directed to a pharmaceutical combination comprising bretylium and bethanidine sulfate. The bethanidine sulfate acts synergistically to intensify the anti-fibrillatory action of bretylium as well as the sympathetic blocking effect of bretylium. This combination increases the anti-adrenergic effect of bretylium alone when and if tolerance to this effect of bretylium develops. This may also be useful in treating hypertension, angina pectoris and lowering vascular impedence.

The present invention is still further directed to a method for treating and/or preventing shock in a human or animal patient. The method comprises administering a pharmaceutical combination comprising a bretylium cation or a source of a bretylium cation, a facilitating anion or a source of a facilitating anion, and an anti-hypotensive agent and/or a β-receptor blocker or a source of an anti-hypotensive agent and/or a β-receptor blocker to a human or animal patient in need thereof. The pharmaceutical combination is characterized in that the facilitating anion is less hydrophilic than a tosylate anion; and the bretylium cation or the source of the bretylium cation, the facilitating anion or the source of the facilitating anion, and the anti-hypotensive agent and/or the β-receptor blocker or the source of the anti-hypotensive agent and/or the β-receptor blocker together are present in said pharmaceutical combination in a therapeutically effective amount. Preferably, the pharmaceutical combination is administered for the treatment and/or prevention of septic shock, hemorrhagic shock, cardiogenic shock or hypovolemic shock.

It is important to note that any of the pharmaceutical compositions or kits of the present invention may also preferably comprise one or more of the following, alone or in any appropriate combination: a neutralizing agent, a buffering agent, an anti-hypotensive agent and/or a β-receptor blocker. Here, the bretylium cation, the facilitating anion, the neutralizing agent, the buffering agent, the anti-hypotensive agent and/or the β-receptor blocker together are present in the pharmaceutical composition in a therapeutically effective amount (or, in the case of a kit, the bretylium cation, the facilitating anion, the neutralizing agent, the buffering agent, the anti-hypotensive agent and/or the β-receptor blocker are present in the kit in amounts such that their combination is therapeutically effective after they are administered). For kits, the preferred order of administration would be to administer the neutralizing agent and the buffer first to adjust the pH of the stomach. A facilitating anion may or may not be added along with the neutralizing agent and the buffer. For example, prior to the administration of a salt containing a bretylium cation and a facilitating anion of the invention, it would be preferred to administer a commercially available Alka Seltzer®, which generally contains a neutralizing agent, a citric buffer and aspirin. However, those skilled in the art will appreciate that the order of application of the components in the kit need not be in any specific order.

Other objects and features of this invention will be in part apparent and in part pointed out hereinafter.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is an electrocardiogram of a dog showing the effect on atrial fibrillation that was observed after administering via injection a composition containing roughly: (a) 15 mg of bretylium tosylate per kg of dog, and (b) 6.5 mg of aspirin per kg of dog.

FIG. 2 is an electrocardiogram of a dog chosen as a control and shows normal sinus rhythm.

FIG. 3 is an electrocardiogram of a dog taken immediately after painting a dilute solution of aconitine on the surface of the right atrium.

FIG. 4 shows the electrocardiogram of the dog with sustained atrial fibrillation after painting with aconitine. After approximately 40 seconds, spontaneous sustained atrial fibrillation was induced after a short burst of atrial tachycardia.

FIG. 5 shows continued, sustained atrial fibrillation lasting 53 minutes after application of aconitine to the right atrium.

FIG. 6 shows sustained atrial fibrillation in the dog for 40 minutes, then a 15 mg/kg dose of bretylium lauryl sulfate salt was given orally after observing 53 minutes of atrial fibrillation.

FIG. 7 shows that 19 minutes and 24 seconds after administration of oral bretylium lauryl sulfate salt, the dog spontaneously came out of atrial fibrillation and regained normal sinus rhythm.

FIG. 8 shows that the dog maintained a normal sinus rhythm 46 minutes after administration of the bretylium lauryl sulfate salt, even after attempts to reinitiate atrial fibrillation with electrical stimulation.

FIG. 9 demonstrates that ventricular or atrial fibrillation did not occur in a dog despite maximum electrical stimulation (50 milliamps) after administration of Bretylium Salicylate.

FIG. 10 demonstrates that ventricular atrial fibrillation did not occur in a dog despite maximum electrical stimulation (50 milliamps) after administration of Bretylium and Aspirin.

FIG. 11 demonstrates that ventricular or atrial fibrillation did not occur in a dog despite maximum electrical stimulation (50 milliamps) after administration of Bretylium Lauryl Sulfate.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Past efforts to orally administer bretylium drugs have failed due to poor and/or unpredictable absorption in the gastrointestinal tract. For example, when conventional bretylium-containing drugs (particularly unformulated bretylium tosylate) have been administered orally, the active component of the drugs (i.e., the bretylium cation) has typically exhibited poor and/or unpredictable uptake in the gastrointestinal tract. This, along with the orthostatic hypotension side-effect of these drugs, have made oral self-administration difficult, thereby largely limiting the use of the drugs to parenteral administration in clinical emergencies when other antiarrhythmic agents have failed.

Unlike previous oral formulations of bretylium compounds, such as bretylium tosylate, the pharmaceutical compositions and kits of the present invention are uniquely adapted for oral administration. In addition, they often tend to exhibit superior activity, time for onset of action, potency, safety, and/or therapeutic effectiveness relative to conventionally used quaternary ammonium formulations (particularly previously-tried oral formulations such as bretylium tosylate). In many instances, the compositions and kits of this invention are especially advantageous because they may be self-administered as needed (for example, at a person's residence or place of work to prevent sudden cardiac death and/or non-fatal myocardial infarction) without the assistance of a health care professional.

Hypothesized Mechanisms of Action

Bretylium ion, if taken internally, must pass through the intestine to the bloodstream, and from there, to the targeted heart tissue. Bretylium ion may be released internally from the dissolution of bretylium tosylate, its most common commercially available form. Macroscopic quantities of ions can only be transferred from one phase to another in neutral combinations. Otherwise, the phases become electrically charged. The uncompensated transfer of an electrically charged ion is energetically very unfavorable. Bretylium salts dissociate to release the quaternary cations in solution. In accordance with the invention, it has been discovered that these therapeutic cations can be transferred across a lipid barrier when in the company of one or several facilitating anions. Use of bretylium with a much less hydrophilic or actually hydrophobic facilitating anion or anions results in improved and increased transfer rates across the biological membranes of interest.

In the aqueous contents of the gastrointestinal tract (particularly the stomach and intestine), orally administered bretylium tosylate dissociates to the bretylium cation and the tosylate anion (or the other anion in the bretylium-cation source). To provide the desired therapeutic effect, however, the bretylium cation must be absorbed from the aqueous contents of the gastrointestinal tract through the lipid phase mucosa of the gastrointestinal tract into the blood, and then transferred from the blood to the target cells (typically (a) the sympathetic ganglia and their postganglionic adrenergic neurons, and (b) cardiac cells). Absorption of the bretylium cation from the gastrointestinal tract into the blood requires that the hydrophilic bretylium cation cross the lipophilic lipid phase boundary of the gastrointestinal tract. It has been discovered that this absorption (or crossing of the lipid phase boundary) can be improved if the bretylium cation is combined with one or more suitable types of anions (i.e., facilitating anions) resulting in a bretylium-cation/facilitating-anion combination that is more lipophilic, or less hydrophilic, than bretylium tosylate. Hydrophilicity of an anion is reduced either by spreading the negative charge over a number of atoms, or by attaching uncharged, weakly polar residues, such as alkyl groups, or both.

It is hypothesized that the bretylium cation and the facilitating anion in the gastrointestinal tract can exist in the form of separate ions, ion pairs, micelles, or otherwise. When the bretylium cation enters the lipid phase, however, it does so as a bretylium-cation/facilitating-anion combination in the form of ion pairs and/or higher ion aggregates, such as inverse micelles. These bretylium-cation/facilitating-anion combinations possess a neutral or substantially neutral charge. In addition, these bretylium-cation/facilitating-anion combinations are more lipophilic, or less hydrophilic, than bretylium tosylate. A partition coefficient can be utilized to predict how well the facilitating anion will work in comparison to an anion coupled with the quaternary ammonium cation.

It is believed that the anions of the invention should have a widespread charge distribution over the molecule, such that when it aggregates with the quaternary ammonium cation, the combination has weak affinity to water (i.e., the combination has a slight affinity to water, little affinity to water, or essentially no affinity to water) and/or the combination is non-polar. One such anion would be 2,4,6 trinitrophenol, however, this anion is known to be toxic. Non-toxic anions capable of forming about aggregates having a low affinity for water are the focus of this invention.

When the bretylium cation and facilitating anion are ingested and ionized in the absence of a neutralizing agent, hydrochloric acid present in the stomach converts a portion of the ionized anions to the corresponding conjugate acid of the anions, which is then largely absorbed by the lipid mucosa in the intestine. As these anions are converted to their conjugate acid form and absorbed, additional anions are then converted to their conjugate acid, and, in turn, absorbed in the intestine. If the anions are too readily converted to their conjugate acid form and/or the pH of the gastrointestinal tract is too low, the hydrophilic chloride anions will effectively be the only anions available for combination with the bretylium cation (if tosylate anions are also present, they too will be converted into their conjugate acid, ρ-toluenesulfonic acid, and, in turn, absorbed in the intestine). Because the bretylium cation cannot be spacially separated from a counterion, and the chloride anions are not readily removed from the aqueous phase, the bretylium cation remains in the aqueous fluid of the stomach and intestine and is ultimately not absorbed. To reduce or eliminate this problem, a neutralizing agent may be administered to increase the pH of the stomach. It is believed that such a pH increase enhances the absorption of the bretylium cation by reducing the amount of the facilitating anion that is converted to its conjugate acid such that a larger portion of the facilitating anion remains available to form the bretylium-cation/facilitating-anion combination.

It is further hypothesized that the compositions and kits of this invention not only enhance the absorption of the bretylium cation from the gastrointestinal tract into the blood, but also enhance the permeation of the bretylium cation from the blood through the capillary walls and the target tissue (the target tissue being myocardial cells, etc.). For example, the di(2-ethylhexyl)sulfosuccinate anion promotes the formation of water-in-oil emulsions. Such emulsions generally consist of droplets having an aqueous core surrounded by di(2-ethylhexyl)sulfosuccinate anions, with the anionic sulfonate groups directed inwardly toward the core center and the hydrocarbon groups directed outwardly from the core, in contact with the oil or lipid bulk phase. The core typically contains a sufficient number of cations to provide the whole assembly with a neutral charge. Such emulsion droplets generally have a radius ranging from about 10×10⁻⁸ cm to about 30×10⁻⁸ cm. Because the typical cell wall has a hydrophobic core bounded by a film having a thickness of about 30×10⁻⁸ cm, a closed emulsion droplet may not form in such a film since the film is too thin to surround the droplet. It is hypothesized, however, that a short cylinder of di(2-ethylhexyl)sulfosuccinate anions may form instead, with the anionic sulfonate groups directed inwardly toward an aqueous core and their hydrocarbon groups directed outwardly toward the lipid of the cell wall, and with the two ends of the cylinder open. One of the open ends is directed outward and the other is directed into the cell. Such a structure would act as a conduit through which the bretylium cation could reach the interior of target cells.

It is additionally hypothesized that these emulsion droplets and/or cylinders also may form in the mucosa of the intestine, with bretylium acting as the neutralizing cation, thereby promoting the absorption of the bretylium cation through the intestinal walls in a similar manner as in the walls of the target cells.

The Compositions of the Present Invention

The compositions of the present invention comprise a bretylium cation and a facilitating anion and, optionally, one or more neutralizing agent(s), buffering agent(s), anti-hypotensive agent(s) and/or a β-receptor blocker. Generally, the composition of the present invention comprises from about 1% to about 60% bretylium cation and from about 1% to about 60% facilitating anion. Preferably, the composition comprises from about 1% to about 90% of a salt of the bretylium cation and facilitating anion. Optionally and preferably, the composition of the present invention may also include from about 0.01% to about 75% neutralizing agent, from about 0.01% to about 30% buffering agent, from about 0.0% to about 0.5% anti-hypotensive agent and from about 0.0% to about 1.0% β-receptor blocker, with any combination of the preceding considered part of the invention. For example, in a preferred embodiment, a composition of the present invention comprises from about 10% to about 60% bretylium cation, from about 5% to about 60% facilitating anion, from about 30% to about 75% neutralizing agent and from about 0.01% to about 1.0% β-receptor blocker. In another preferred embodiment, the compositions and kits of the present invention comprise from about 10% to about 40% by weight bretylium cation, from about 5% to about 30% by weight facilitating anion, from about 40% to about 70% by weight neutralizing agent and from about 0.1% to about 1.0% by weight β-receptor blocker.

Stated another way, the composition of the present invention may be described as a 1.0 gm tablet comprising from about 1 to about 900 mg salt of the bretylium cation and facilitating anion. Optionally and preferably, the composition may also include from about 0.01 to about 500 mg of neutralizing agent, from about 0.01 to about 300 mg of buffering agent, from about 0 to about 5 mg of anti-hypotensive agent and from about 0 to about 10 mg of β-receptor blocker with a remainder of the composition comprising fillers, disintegrants, binding agents, adhesives, wetting agents, lubricants, glidants, anti-adherents, enteric coatings, inert diluents and/or surface active/dispersing agents. Any combination of the above is considered part of the invention.

Particularly preferred compositions fall within one of the following categories:

-   -   (1) Compositions comprising a bretylium cation, a facilitating         anion, a neutralizing agent and preferably, a buffering agent.     -   (2) Compositions comprising a bretylium cation, a facilitating         anion, and an anti-hypotensive agent.     -   (3) Compositions comprising a bretylium cation, a facilitating         anion, a neutralizing agent, a buffering agent and an         anti-hypotensive agent.     -   (4) Compositions comprising a bretylium cation, a facilitating         anion, and a β-receptor blocker.     -   (5) Compositions comprising a bretylium cation, a facilitating         anion, an anti-hypotensive agent, and a β-receptor blocker.     -   (6) Compositions comprising a bretylium cation, a facilitating         anion, a neutralizing agent, and an anti-hypotensive agent.         Here, it is especially preferred for the compositions to also         comprise a buffering agent.     -   (7) Compositions comprising a bretylium cation, a facilitating         anion, a neutralizing agent, and a β-receptor blocker. Here, it         is especially preferred for the compositions to also comprise a         buffering agent.     -   (8) Compositions comprising a bretylium cation, a facilitating         anion, a neutralizing agent, an anti-hypotensive agent, and a         β-receptor blocker. Here, it is especially preferred for the         compositions and kits to also comprise a buffering agent.     -   (9) Compositions comprising a bretylium cation, an         acetylsalicylate anion and a β-receptor blocker.     -   (10) Compositions comprising a bretylium cation, aspirin (i.e.,         “acetylsalicylic acid”) or an alkali metal salt of         acetylsalicylic acid and a β-receptor blocker.     -   (11) Compositions comprising a bretylium cation, an         acetylsalicylate anion, a β-receptor blocker and optionally an         anti-hypotensive agent.     -   (12) Compositions comprising a bretylium cation and an         acetylsalicylate anion.     -   (13) Compositions comprising a bretylium cation and at least one         β-receptor blocker (particularly propranolol, atenolol, esmolol,         metoprolol, labetalol, talinolol, timolol, acebutolol,         dichloroisoproterenol, pronethalol, sotalol, oxprenolol,         alprenolol, practolol, nadolol, pindolol, penbutolol or         carvedilol) and/or combined with bethanidine sulfate to         synergize anti-fibrillatory and sympathetic blocking actions of         bretylium.         Kits of the Invention

The current invention includes the concept of a kit, wherein the bretylium cation of the invention may be provided as a salt of a non-facilitating anion (such as bromide or chloride) and the facilitating anion may be provided as a salt of a non-quaternary ammonium salt (such as sodium or potassium). The kit may include such items as neutralizing agents, buffers, anti-hypotensive agents and β-receptor blockers.

The bretylium cation, the neutralizing agent, the buffering agent, the anti-hypotensive agent, and/or the β-receptor blocker and the facilitating anion together are present in the kit in a therapeutically effective amount such that their combination is therapeutically effective after they are administered. The individual components (e.g., the bretylium cation, the neutralizing agent, buffering agents, anti-hypotensives, etc.) may be any convenient combination of compositions in any convenient formulation such as pills, syrups, liquids or aerosols, and may be administered in any appropriate manner, e.g., parenterally, orally or by inhalation of an aerosol. Such compositions may include one or more of the individual components of the invention and each kit may have multiple compositions in it.

Source of the Bretylium Cations

The compositions and kits of this invention may contain the bretylium cation in the form of a pharmaceutically acceptable material that either comprises the bretylium cation itself or is capable of forming the bretylium cation after being administered to the intended recipient (and, consequently, when a composition or kit is referred to herein as comprising the bretylium cation, it should be understood that the composition or kit may either comprise the bretylium cation itself or be capable of forming the bretylium cation after being administered to the intended recipient). Thus, for example, when intended for oral administration, the pharmaceutically acceptable material should release the bretylium cation into the aqueous contents of the gastrointestinal tract. Suitable materials include, for example, pharmaceutically acceptable salts of the bretylium cation (e.g., bretylium tosylate, bretylium di(2-ethylhexyl) sulfosuccinate, or bretylium salicylate), and solutions or suspensions comprising the bretylium cation. Pharmaceutical grade bretylium tosylate is commercially available from, for example, Ganes Chemicals, Inc., Carlstadt, N.J. Alternatively, bretylium tosylate may be prepared, for example, by reacting o-bromobenzylethylmethylamine with methyl tosylate, as discussed in U.S. Pat. No. 3,038,004.

When the material is a pharmaceutically acceptable salt other than bretylium tosylate, the anion of the salt preferably has little or no tendency to form a covalent compound with the bretylium cation. Such salts may be prepared, for example, by using a conventional double displacement reaction, wherein a bretylium salt (e.g., bretylium tosylate) is reacted with a suitable acid or alkali metal salt (preferably a sodium salt) of the desired anion. Bretylium-cation-containing materials, which have been approved by the Food and Drug Administration for use in other medicines or foods, are generally most preferred.

Source of the Facilitating Anion

The compositions and kits of this invention may contain the facilitating anion in the form of a pharmaceutically acceptable material that either comprises the facilitating anion itself or is capable of forming the facilitating anion after being administered to the intended recipient (and, consequently, when a composition or kit is referred to herein as comprising a facilitating anion, it should be understood that the composition or kit may either comprise the facilitating anion itself or be capable of forming the facilitating anion after being administered to the intended recipient). It is preferred that the facilitating anion have a weak affinity for water and/or be non-polar, and it is particularly preferred for the facilitating anion to be less hydrophilic than the tosylate anion. Such an anion, when ingested with the bretylium cation (either in the form of a compound containing a salt of the bretylium cation and the facilitating anion, or separate salts of the bretylium cation and the facilitating anion), tends to form cation/facilitating-anion combinations capable of, for example, crossing the lipid phase boundary of the gastrointestinal tract to enter the bloodstream, and crossing the lipid barriers of the capillary membranes and myocardial cell membranes of the heart. Preferably, the facilitating anion forms bretylium cation/facilitating anion combinations having a neutral or substantially neutral charge. Such combinations are also preferably more lipophilic (or less hydrophilic) than bretylium tosylate. Partition coefficient measurements can help predict whether a particular anion will facilitate the transfer of the bretylium cation. Facilitating-anion-containing materials, which have been approved by the Food and Drug Administration for use in other medicines or foods, are generally most preferred.

It is particularly preferred for the facilitating anion to have at least one of the following features:

-   -   (1) The facilitating anion is the conjugate base of an acid         having a pK_(a) value of less than about 5, more preferably less         than about 4, and still more preferably less than about 3. Where         a neutralizing agent is not administered, it is preferred for         the facilitating anion to be the conjugate base of an acid         having a pK_(a) value of less than about 1, more preferably less         than about 0, and still more preferably less than about −1.         Although the pK_(a) values associated with suitable facilitating         anions may be less than about −10, most suitable facilitating         anions will have a pK_(a) value of about −10.     -   (2) The facilitating anion has a well-distributed charge to         reduce its hydrophilicity. A particularly preferred example of         such an anion is the salicylate anion.     -   (3) Alternatively, the facilitating anion comprises at least one         alkyl group that comprises at least 10 carbon atoms. A preferred         example of such an anion is the dodecylsulfate anion.     -   (4) The facilitating anion has an organic/aqueous phase         distribution constant (“K”) that is greater than the         organic/aqueous phase distribution constant associated with the         tosylate anion (i.e., greater than about 320). In a particularly         preferred embodiment, the facilitating anion has a K value which         is greater than about 500, more preferably greater than about         700, still more preferably greater than about 800, and still         even more preferably greater than about 1000. Although the K         values associated with suitable facilitating anions may be         greater than about 10⁶, the most suitable facilitating anions         have a K value which is less than about 10⁶. To determine the K         value for a particular anion, a small amount of         methyltridecylammonium chloride (“Q⁺Cl⁻”) and a small amount of         the methyltridecylammonium salt of the anion (“Q⁺X⁻”) are added         to a mixture of water and octanol. The mixture is allowed to         separate, and the concentrations of the chloride ion and the         anion in each phase are then measured. The K value is calculated         using the formula: K=[X⁻, oct.] [Cl⁻, aq.]/[X⁻, aq.] [Cl⁻,         oct.], wherein the quantities in brackets are concentrations.         The K value for the salicylate anion, for example, is reported         to be greater than 1000. A more extensive discussion of the         procedure for determining K values can be found in, for         example, C. J. Coetzee and H. Freisee, Anal. Chem., Vol. 41,         Page 1128 (1969) (incorporated herein by reference).

Examples of suitable facilitating anions include, but are not limited to, the following: R¹OSO₃ ⁻, R²SO₃ ⁻,

-   -   a pseudo-icosahedral carborane anion (CB₁₁H₁₂ ⁻), and     -   a substituted pseudo-icosahedral carborane anion.         In the above-formulas, R¹, R², R³, R⁴, R⁶, R⁷, R⁸, R⁹, R¹⁰, R¹¹,         R¹², R¹³, R¹⁴, R¹⁵, R¹⁶, R¹⁷, and the substituent (or         substituents) of the substituted pseudo-icosahedral carborane         anion are independently hydrocarbyl or substituted hydrocarbyl;         and R⁵ and R¹⁸ are independently hydrogen, hydrocarbyl, or         substituted hydrocarbyl. In a particularly preferred embodiment,         R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R⁹, R¹⁰, R¹¹, R¹², R¹³, R¹⁴,         R¹⁵, R¹⁶, R¹⁷, and the substituent (or substituents) of the         substituted pseudo-icosahedral carborane anion are independently         hydrocarbyl; and R¹⁸ is hydrogen. In such an embodiment, R¹, R²,         R³, R⁴, R⁵, R⁶, R⁷, R⁸, R⁹, R¹⁰, R¹¹, R¹², R¹³, R₁₄, R¹⁵, R¹⁶,         R¹⁷, and the substituent (or substituents) of the substituted         pseudo-icosahedral carborane anion are preferably independently         selected from the group consisting of alkyl, alkenyl, alkynyl,         cycloalkyl, cycloalkenyl, aryl, arylalkyl, arylalkenyl, or         arylalkynyl. The preferred aryl is phenyl. The aryl moiety may         be unsubstituted or substituted with one or more radicals         selected from the group consisting of alkyl, alkenyl, alkynyl,         cycloalkyl, and cycloalkenyl.

In a preferred embodiment, R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R⁹, R¹⁰, R¹¹, R¹², R¹³, R¹⁴, R¹⁵, R¹⁶, R¹⁷, and the substituent (or substituents) of the substituted pseudo-icosahedral carborane anion are independently a residue of a fatty acid formed by removing a carboxylic acid group from the fatty acid.

In another preferred embodiment, the facilitating anion comprises an anion selected from the group consisting of (C₁₀-C₃₀)alkylsulfate anions, (C₁₀-C₃₀)alkylsulfonate anions, (C₆-C₁₂)alkylsulfosuccinate anions, salicylate anions, (C₁-C₃₀)alkylsalicylate anions, (C₁₀-C₃₀)alkylphosphate anions, di(C₈-C₁₂)alkylphosphate anions, di(C₁₀-C₃₀)alkanoylphosphatidate anions, (C₈-C₂₂)alkylmaleate anions, di(C₄-C₁₂)alkylmaleate anions, α-keto (C₉-C₂₁)carboxylate anions, α-hydroxy (C₉-C₂₁)carboxylate anions, (C₁₂-C₂₂)alkylmalonate anions, and (C₁-C₁₈)alkylpseudo-icosahedral carborane anions.

Still more preferably, the facilitating anion comprises an anion selected from the group consisting of (C₁₀-C₃₀)alkylsulfate anions, (C₁₀-C₃₀)alkylsulfonate anions, (C₆-C₁₂)alkylsulfosuccinate anions, salicylate anions, (C₁₀-C₃₀)alkylphosphate anions, di(C₈-C₁₂)alkylphosphate anions, and di(C₈-C₂₂)alkanoylphosphatidate anions.

Still even more preferred facilitating anions comprise an anion selected from the group consisting of the di(2-ethylhexyl)sulfosuccinate anion 2; the salicylate anion 3; the di(2-ethylhexyl) phosphate anion 4; the lauryl sulfate anion 5; the hexadecylsulfonate anion 6; the dipalmitoyl phosphatidate anion 7; and the acetylsalicylate anion 8:

In a particularly preferred embodiment, the facilitating anion is the di(2-ethylhexyl)sulfosuccinate anion 2. In another particularly preferred embodiment, the facilitating anion is the salicylate anion 3. In yet another particularly preferred embodiment, the facilitating anion is the lauryl sulfate anion 5. In still a further particularly preferred embodiment, the facilitating anion is the acetylsalicylate anion 8. It has been found in accordance with this invention that these anions (and especially the salicylate anion, the lauryl sulfate anion, and the acetylsalicylate anion), in general, tend to synergistically enhance the therapeutic effects of the bretylium cation by, for example, synergistically increasing the ventricular fibrillation threshold and synergistically prolonging the effective ventricular refractory period.

When intended for oral administration, the source of the facilitating anion preferably is a pharmaceutically acceptable material that releases the facilitating anion into the aqueous contents of the gastrointestinal tract. Non-limiting examples of suitable facilitating anion sources include the pharmaceutically acceptable salts of the facilitating anion (e.g., the alkali metal salts, particularly the sodium salts, of the facilitating anion), and solutions or suspensions comprising the facilitating anion. When the source is a salt, the counterion paired with the facilitating anion preferably has little or no tendency to associate with the facilitating anion. Such salts may be prepared by conventional means from the conjugate acid of the facilitating anion (e.g., reacting an appropriate base with the conjugate acid).

In one of the most preferred embodiments, the pharmaceutical composition or kit contains the acetylsalicylate anion in the form of acetylsalicylic acid (i.e., aspirin) or an alkali metal salt of acetylsalicylic acid (e.g., a sodium, potassium, calcium or magnesium salt of acetylsalicylic acid). One reason for this particular preference stems from the fact that in addition to enhancing the effects of the bretylium cation (apparently synergistically), the acetylsalicylate anion reduces or entirely blocks platelet aggregation (a common cause of cardiac complications). Preferably, the acetylsalicylic acid or alkali metal salt of acetylsalicylic acid is given prior to or concomitantly with the administration of the bretylium. Although the acetylsalicylate anion can be provided in molar ratios under 1 (e.g., from about 0.5 to 1), it is preferred to use at least a 1:1 molar ratio of acetylsalicylate anion to bretylium cation, most preferably a slight molar excess of acetylsalicylate anion (i.e., a molar ratio of acetylsalicylate anion to bretylium cation of from about 1.1 to about 1.5). For example, in a preferred embodiment of the present invention comprising a 1000 mg dosage of bretylium (i.e., 15 mg/kilo in a 70 kg human), an 800 mg dosage of acetylsalicylic acid or alkali metal salt of acetylsalicylic acid should preferably be applied.

Sodium di(2-ethylhexyl)sulfosuccinate is commercially available from Aldrich Chemical Co., Milwaukee, Wis. Potassium di(2-ethylhexyl)sulfosuccinate can be prepared from the sodium salt by recrystallization from aqueous solution in the presence of an excess of potassium chloride.

Salicylic acid and sodium salicylate are both commercially available from Aldrich Chemical Co. Potassium salicylate can be prepared by treating a hot, concentrated solution of salicylic acid with an equivalent amount of potassium hydroxide, preferably as a concentrated solution, and then cooling to separate potassium salicylate.

Sodium dodecylsulfate is commercially available from Aldrich Chemical Co. Potassium dodecylsulfate can be prepared by recrystallizing the sodium salt in the presence of an excess of potassium chloride.

Di(2-ethylhexyl)phosphoric acid is commercially available from Aldrich Chemical Co. Sodium di(2-ethylhexyl)phosphate, can be prepared by treating a toluene solution of the acid with an excess of sodium hydroxide as an aqueous solution. A 2-phase system results, with the sodium salt in the toluene phase. Separation of the phases followed by distillation of the toluene yields a residue that is sodium di(2-ethylhexyl)phosphate. The potassium salt is obtained analogously, except that a potassium hydroxide solution is used in the place of the sodium hydroxide solution.

1-Hexadecylsulfonic acid sodium salt is commercially available from Aldrich Chemical Co. Potassium 1-hexadecylsulfonate can be obtained from the sodium salt by recrystallization in the presence of a small excess of potassium chloride.

Sodium salts of phosphatidic acids are commercially available from Avanti Polar Lipids, Alabaster, Ala.

It should be recognized that the compositions, kits, and methods of the present invention are not limited to the use of a single type of facilitating anion. If necessary or desirable, two or more different types of facilitating anions can be used.

It should also be recognized that the bretylium cation and the facilitating anion can be from the same compound or from different compounds. For example, the source of the bretylium cation and the source of the facilitating anion may be a single compound comprising the bretylium cation and the facilitating anion, such as a pharmaceutically acceptable salt wherein the bretylium cation is paired with the facilitating anion. Such compounds include, for example:

-   -   a) bretylium di(2-ethylhexyl)sulfosuccinate;     -   b) bretylium salicylate;     -   c) bretylium acetylsalicylate;     -   d) bretylium di(2-ethylhexyl)phosphate;     -   e) bretylium lauryl sulfate; and     -   f) bretylium hexadecylsulfonate.         Source of the β-Receptor Blocker

The compositions and kits of the present invention concerning bretylium may contain one or more pharmaceutically acceptable β-receptor blockers (preferably, a β-receptor blocker that does not antagonize the therapeutic effect of the bretylium cation). It has been found in accordance with this invention that a β-receptor blocker often produces a synergistic improvement in the therapeutic effect of the bretylium cation. For example, a β-receptor blocker tends to (1) synergistically increase the rate at which the bretylium cation affects anti-fibrillatory action, and/or (2) synergistically enhance the anti-fibrillatory action of the bretylium cation.

Suitable β-receptor blockers generally include, but are not limited to, propranolol (also known as “Inderal”), atenolol, esmolol, metoprolol, labetalol, talinolol, timolol, acebutolol, dichloroisoproterenol, pronethalol, sotalol, oxprenolol, alprenolol, practolol, nadolol, pindolol, penbutolol, and carvedilol. Preferably, the β-receptor blocker comprises propranolol, atenolol, esmolol, metoprolol, talinolol, timolol, or acebutolol. In a particularly preferred embodiment, the β-receptor blocker comprises propranolol. In another particularly preferred embodiment, the β-receptor blocker comprises esmolol (particularly in instances where the composition is being administered via injection and/or the facilitating anion is lauryl sulfate, sulfosuccinate, or salicylate). In yet a further particularly preferred embodiment, the β-receptor blocker comprises metoprolol.

Propranolol is commercially available from, for example, Wyeth-Ayerst Laboratories, Philadelphia, Pa. Atenolol is commercially available from, for example, Zeneca Pharmaceuticals, Wilmington, Del. Esmolol is commercially available from, for example, Baxter Healthcare Corp., Deerfield, Ill. Metoprolol is commercially available from, for example, Novartis, East Hanover, N.J. Labetalol is commercially available from, for example, Schering-Plough Pharmaceuticals, Madison, N.J. Acebutolol is commercially available from, for example, Wyeth-Ayerst Laboratories. Carvedilol is commercially available from, for example, SmithKline Beecham, Philadelphia, Pa. Sotalol is commercially available from, for example, Berlex Laboratories, Inc., Wayne, N.J. Nadolol is commercially available from, for example, Bristol-Myers Squibb Co., Stamford, Conn.

Source of the Neutralizing Agent

The compositions and kits of the present invention (particularly those intended to be orally administered) may optionally contain one or more neutralizing agents. The neutralizing agent may be any pharmaceutically acceptable material that increases the pH of the stomach when ingested, and that is chemically compatible with the bretylium cation and the facilitating anion selected. Preferably, the neutralizing agent is physiologically inert other than for pH adjustment purposes, and is not absorbed or only minimally absorbed from the gastrointestinal tract. Examples of particularly preferred neutralizing agents are those selected from the group consisting of pharmaceutically acceptable alkali metal carbonates (e.g., sodium bicarbonate or potassium hydrogen carbonate); alkali metal citrates (e.g., sodium citrate); alkali metal phosphates (e.g., disodium phosphate); alkali metal salts of carboxylic acids (e.g., alkali metal salts of acetic acid, tartaric acid or succinic acid); alkaline earth metal hydroxides (e.g., magnesium hydroxide); and mono-, di-, and polyamino-sugars (e.g., methyl glucamine, i.e., meglumine). In one of the more preferred embodiments, the neutralizing agent comprises sodium bicarbonate, sodium citrate, or a combination thereof, which are each non-toxic and have a lower equivalent weight than most other suitable neutralizing agents. For example, in a preferred embodiment, it has been found that a commercially available Alka Seltzer® tablet comprising sodium bicarbonate, citric acid and aspirin can act as a sufficient neutralizing agent.

A neutralizing agent permits the use of a broader class of facilitating anions. More specifically, because the preferred facilitating anions are conjugate bases of acids having a pK_(a) value lower than or equal to the ambient pH of the stomach, a neutralizing agent can be used to temporarily increase the stomach pH in a subject to expand the range of suitable facilitating anions. When a neutralizing agent is employed, the facilitating anion selected preferably is the conjugate base of an acid having a pK_(a) value at least about one unit less than the ambient pH as adjusted by the neutralizing agent, more preferably the conjugate base of an acid having a pK_(a) value at least about 1.5 units less than the ambient pH as adjusted by the neutralizing agent, and still more preferably the conjugate base of an acid having a pK_(a) value at least about 2 units less than the ambient pH as adjusted by the neutralizing agent.

Source of the Buffering Agent

The composition and kits of the present invention (particularly those intended for oral administration, and even more particularly those containing a neutralizing agent) may optionally contain one or more buffering agents to prevent an excessive increase in the pH of the aqueous contents of the stomach. The buffering agent may comprise any pharmaceutically acceptable buffering agent. Suitable buffering agents include, but are not limited to, pharmaceutically acceptable acids (e.g., citric acid). In a particularly preferred embodiment, the buffering agent is a pharmaceutically acceptable acid having a pK_(a) value of at least about 1 unit (and more preferably at least about 2 units) greater than the pK_(a) value of the conjugate acid of the facilitating anion selected. Even more preferably, the buffering agent is an acid having a pK_(a) value of from about 4.5 to about 5.5.

Source of the Anti-Hypotensive Agent

The compositions and kits of the present invention may optionally contain one or more pharmaceutically-acceptable anti-hypotensive agents, which reduce or eliminate orthostatic hypotension caused by the bretylium cation. The anti-hypotensive agent preferably operates to reduce or eliminate the orthostatic hypotension by blocking the uptake of the bretylium cation into the sympathetic nerves. Suitable anti-hypotensive agents include, but are not limited to, tricyclic anti-depressant compounds selected from the group consisting of protriptyline, mazindol, amitriptyline, nortriptyline, desipramine, with protriptyline being especially preferred. Protriptyline is commercially available from, for example, Sidmak Labs, Inc., East Hanover, N.J.

In a particularly preferred embodiment, the anti-hypotensive agent(s), in addition to reducing or eliminating orthostatic hypotension caused by the bretylium cation, also enhance the therapeutic effect of the bretylium cation by, for example, raising the electrical ventricular fibrillation threshold. Anti-hypotensive agents, particularly tricyclic anti-depressant compounds discussed above, often synergize the therapeutic effect of the bretylium cation, thereby lowering the dose of the bretylium cation needed, for example, to suppress ventricular tachyarrhythmias.

Epinephrine, a synthetic sympathomimetic adrenergic drug, may also be used to reverse orthostatic hypotension.

Utility of the Compositions and Kits of the Present Invention

The compositions and kits of the present invention are useful for, but not limited to, treating conditions (i.e., medical disorders or otherwise) which have conventionally been treated by administering the bretylium cation (particularly in the form of bretylium tosylate injectable compositions). In general, the compositions and kits are useful where it is desirable to accomplish one or more of the following:

-   -   1. Prevent sudden cardiac death.     -   2. Prevent and/or treat myocardial infarction.     -   3. Prevent and/or treat congestive heart failure (particularly         by inducing sympathetic blockade), such as by reducing oxidative         metabolism in the heart by blocking norepinephrine release.     -   4. Prevent and/or treat ventricular fibrillation (particularly         by raising the ventricular fibrillation threshold).     -   5. Prevent and/or treat ventricular arrhythmia in general.     -   6. Prevent and/or treat ventricular tachycardia.     -   7. Prevent and/or treat ventricular premature heartbeats.     -   8. Prevent and/or treat atrioventricular dissociation.     -   9. Prevent and/or treat multifocal ectopic beats.     -   10. Prevent and/or treat premature ventricular extrasystoles.     -   11. Prevent and/or treat bigeminal rhythm.     -   12. Prevent and/or treat trigeminal rhythm.     -   13. Prevent and/or treat angina pectoris (most notably by         sympathetic blockade; optionally with the administration of         bethanidine sulfate).     -   14. Prevent and/or treat coronary insufficiency (most notably by         sympathetic blockade).     -   15. Prevent and/or treat sympathetically induced pain, such as         with causalgia.     -   16. Restore and/or maintain normal sinus rhythm.     -   17. Increase the effective ventricular refractory period.     -   18. Increase the sinus automaticity transiently.     -   19. Prolong the Purkinje action potential duration.     -   20. Induce post-ganglionic sympathetic blockade, thereby         reducing oxidative metabolism in the heart, reducing the heart         rate, and reducing the blood pressure.     -   21. Block the sympathetic nervous system, typically by blocking         the release of norepinephrine at sympathetic nerve endings or         ganglia, and/or by blocking β-receptors.     -   22. Reduce vascular impedance, and, in particular, reduce         coronary resistance.     -   23. Increase the ventricular fibrillation threshold.     -   24. Prolong the action potential duration of cardiac cells.     -   25. Prevent the sympathetic reflex by blocking the same, which         occurs when congestive heart failure increases central venous         pressure or atrial pressure inducing coronary artery         vasoconstriction. Activation of the sympathetic reflex causes         reflex coronary constriction with a decrease in coronary blood         flow that perpetuates congestive heart failure in a vicious         cycle by increasing myocardial ischemia, which would then         further reduce contractile strength and pumping capacity of the         myocardium, thereby further augmenting congestive heart failure.     -   26. Prevent and/or treat the occurrence of shock in a patient,         particularly a patient susceptible to or suffering from septic         shock, hemorrhagic shock, cardiogenic shock and/or hypovolemic         shock.

The pharmaceutical compositions and kits of the present invention are particularly advantageous because they generally act in two separate ways to treat the above conditions: (1) the compositions and kits of the present invention have an anti-fibrillatory effect (i.e., it is believed that the compositions and kits of the present invention directly act on the ionic currents in the myocardial heart cells to prevent and/or treat fibrillation) by blocking potassium outward current and modulating calcium current and (2) the compositions and kits of the present invention have a sympathetic nervous system blocking effect (i.e., it is believed that they block the release of the nerve transmitter norepinephrine from the sympathetic ganglia and nerve endings, thereby reducing or entirely eliminating the coronary artery constriction, platelet aggregation, and/or oxygen waste normally caused by the release of the nerve transmitter).

It also has been discovered in accordance with this invention that the compositions and kits of this invention (particularly those comprising a source of the salicylate anion, and most preferably those comprising an acetylsalicylate anion, less preferably those comprising a source of lauryl sulfate or di(2-ethylhexyl sulfosuccinate)) may be used to prevent and/or treat atrial arrhythmia, most notably atrial fibrillation (as well as atrial tachycardia). Atrial fibrillation is reported to be probably the most common cardiac arrhythmia. Although it is often not a life-threatening arrhythmia, atrial fibrillation is believed to be associated with strokes caused by blood clots forming in areas of stagnant blood collected in the non-contracting atrium as a result of the atrial fibrillation. Atrial fibrillation also is associated with loss of the atrial-ventricular synchrony, and therefore can result in an irregular heart rate and/or a hemodynamically inefficient cardiac performance. In addition, atrial fibrillation may cause, for example, palpitations of the heart, dyspnea (i.e., difficulty in breathing), fatigue, angina pectoris (i.e., pain in the region of the heart), dizziness, or even loss of consciousness. Thus, the use of the compositions and kits of the present invention to prevent and/or treat atrial arrhythmia can ultimately offer several benefits by reducing or eliminating one or more of these conditions. And, the compositions and kits of the present invention may be used without causing the trauma normally associated with many conventionally used techniques for converting atrial fibrillation to sinus rhythm (most notably, shocking the chest wall or implantation of an atrial defibrillator).

It should be recognized that the compositions and kits of this invention may be used in conjunction with or as a replacement for other antiarrhythmic agents, adrenergic neuronal blocking agents (e.g., lidocaine), and/or therapeutic agents useful for the treatment of congestive heart failure (e.g., ACE inhibitors and/or digitalis).

It should further be recognized that these compositions and kits are useful for human treatment, as well as veterinary treatment of companion animals, exotic animals, and farm animals. More preferred recipients include mammals, particularly humans, horses, dogs, and cats.

Dosages

A. Dosage of the Bretylium Cation

The pharmaceutical compositions and kits of the present invention preferably contain the bretylium cation in an amount sufficient to administer from about 0.1 to about 3000 mg (more preferably from about 20 to about 1600 mg, and still more preferably from about 40 to about 1000 mg) of the bretylium cation. When the source of the bretylium cation is bretylium tosylate, the pharmaceutical composition or kit preferably contains from about 0.2 to about 5000 mg (more preferably from about 40 to about 2500 mg, and still more preferably from about 80 to about 2000 mg) of bretylium tosylate.

A daily dose of the pharmaceutical composition or kit preferably administers an amount of the bretylium cation sufficient to provide from about 0.001 to about 50 mg (more preferably from about 0.6 to about 18 mg, and still more preferably from about 1 to about 18 mg) of the bretylium cation per kg of the recipient's body weight per day. When the source of the bretylium cation is bretylium tosylate, a daily dose of the pharmaceutical composition or kit preferably administers from about 0.002 to about 50 mg (more preferably from about 1 to about 30 mg, and still more preferably from about 2 to about 30 mg) of bretylium tosylate per kg of the recipient's body weight per day.

It should be recognized that the preferred daily dose of the bretylium cation will depend on various factors. One such factor is the specific condition being treated. For example, the preferred daily dose of the bretylium cation for an anti-infarction therapeutic effect is from about 1.0 to about 5.0 mg/kg body weight per day, while the preferred daily dose for an anti-fibrillatory therapeutic effect is from about 0.5 to about 50.0 mg/kg body weight per day, typically from about 0.5 to about 30 mg/kg body weight per day, and the preferred daily dose for a sympathetic blockade therapeutic effect is from about 1.0 to about 2.0 mg/kg body weight per day. Other factors affecting the preferred daily dose include, for example, the age, weight, and sex of the subject; the severity of the condition being treated; and the route and frequency of administration. In many instances, the preferred daily bretylium cation dosage will be the same as the dosage employed in injectable bretylium tosylate compositions known to those of ordinary skill in the art for obtaining the desired effect.

The daily dose is preferably administered in the form of from 1 to 4 unit doses (e.g., administration from once every 6 hours to once per day), more preferably from 2 to 3 unit doses (this preference stems from the fact that the elimination half-life of the bretylium cation is from about 10 to 12 hours). When administered orally, the daily dose may be administered in the form of a unit dose of a composition comprising the bretylium cation or as part of a kit comprising a source of the bretylium cation. Unit dosage forms typically administer, for example, a 10, 20, 25, 37.5, 50, 75, 100, 125, 150, 175, 200, 250, 300, 350, or 400 mg dose of the bretylium cation for an average-size human (average-size being about 75 kg). Where the bretylium cation is provided in the form of bretylium tosylate, dosage units are preferably capsules or tablets containing about 120, 240, or 360 mg of bretylium tosylate. The dosage unit form may be selected to accommodate the desired frequency of administration used to achieve the specified daily dosage. It should be recognized that the amount of the unit dosage and the dosage regimen for treating a condition may vary widely and will depend on a variety of factors, including the age, weight, sex, and medical condition of the subject; the severity of the condition; and the route and frequency of administration. For example, subjects with impaired renal function may require a lesser amount of the bretylium cation relative to subjects with normal renal function due to the higher clearance time needed to eliminate the bretylium cation, which is eliminated unchanged in the urine. Preferably, at least an equimolar amount (i.e., a 1:1 molar ratio) or a small molar excess (i.e., from about a 1:1.1 to about a 1:1.5 molar ratio) of the facilitating anion should be provided with the bretylium, and in a preferred embodiment, a 1:2 molar ratio is provided. Less preferably, a 1:0.5 molar ratio could be used, although there would be less facilitating anion present to combine with the bretylium.

In a particularly preferred embodiment, only one unit dosage of the bretylium cation is administered per day. As has been discovered in accordance with this invention, the benefits of the bretylium cation (e.g., increased ventricular fibrillation threshold) can generally be extended over time so that only 1 dose per day is preferred, particularly where the source of facilitating anion is, for example, a source of the salicylate anion, the lauryl sulfate anion, and/or the di(2-ethylhexyl)sulfosuccinate anion. In one of the most preferred embodiments, the benefits of the bretylium cation are extended by administering the bretylium cation with an acetylsalicylate anion (in an especially preferred embodiment, the source of the bretylium cation (e.g., bretylium tosylate) is administered with an acetylsalicylate anion and a β-receptor blocker).

B. The Ratio of Facilitating Anion to Bretylium Cation

The pharmaceutical compositions and kits of the present invention preferably have a molar ratio of the facilitating anion to the bretylium cation of at least about 1.0, more preferably at least about 1.1, still more preferably from about 1.1 to about 4, and still even more preferably from about 1.1 to about 2. For example, when the facilitating anion is an acetylsalicylate anion, it is preferred that the molar ratio of facilitating anion to bretylium cation is at least about 1.0, and more preferably from about 1.1 to about 1.5. Lower molar ratios (i.e., from about 0.5 to about 1.0) may also be used, but provide less facilitating anion.

C. Neutralizing Agent

As noted above, when the compositions or kits of the present invention are administered orally, the composition or kit preferably comprises a neutralizing agent. The neutralizing agent preferably is present in an amount sufficient to increase the pH of the aqueous contents of the stomach after ingestion to a value sufficient to prevent the absorption of a significant fraction of the facilitating anion as its conjugate acid into the gastrointestinal mucosa. More preferably, the amount of neutralizing agent is sufficient to temporarily increase the pH of the aqueous contents of the stomach to at least about 2, more preferably to at least about 3, and still more preferably to at least about 4. In a particularly preferred embodiment, the pH increases to at least about 2 within less than about 1 minute, and remains greater than about 2 for at least about 15 minutes after administration of the neutralizing agent. Although an amount of neutralizing agent sufficient to increase the pH to a value greater than about 7 may be used, the amount preferably does not increase the pH to a value greater than about 7. For most neutralizing agents, an amount of up to about 50 mmole (preferably from about 0.05 to about 50 mmole) is sufficient to achieve the desired pH increase in an average-size human. For example, when using sodium bicarbonate as the neutralizing agent in an average-size human, the sodium bicarbonate preferably is administered in an amount of from about 0.1 to about 4200 mg, more preferably from about 5 to about 4200 mg, still more preferably from about 10 to about 4200 mg, and still even more preferably from about 1000 to about 4200 mg.

It should be recognized that the facilitating anion also may function to increase the pH of the stomach when the facilitating anion is converted into its corresponding conjugate acid. Accordingly, the amount of neutralizing agent required may generally be reduced by increasing the amount of the facilitating anion in the composition. In some embodiments, the preference for a separate neutralizing agent may be entirely eliminated by selection of an appropriate amount of a suitable facilitating anion.

In one embodiment, it is preferred to use sodium bicarbonate as a neutralizing agent in combination with citric acid as a buffering agent as described below and as found commercially, for example, in an Alka Seltzer® tablet. In such an embodiment, the molar ratio of sodium bicarbonate to citric acid is preferably between about 3:1 to about 5:1, with a 4:1 molar ratio most preferred. Thus, a preferred composition of the present invention including from about 1000 mg to about 2000 mg (e.g., about 1250 mg, 1500 mg or 1700 mg) of sodium bicarbonate will contain from about 600 mg to about 1200 mg (e.g., about 750 mg, 900 mg or about 1000 mg) of sodium citrate.

D. Buffering Agents

As noted above, the compositions and kits intended to be administered orally preferably comprise a buffering agent, particularly where a neutralizing agent is also included in the composition or kit. When a buffering agent is used in combination with a neutralizing agent, the molar ratio of buffering agent to neutralizing agent may vary widely. Preferably, the molar ratio of buffering agent to neutralizing agent is from about 0.25 to about 1.5, and more preferably about 1. Typically, the amount of buffering agent should be sufficient to buffer the pH of the stomach between about 2 and 7 upon administration of the neutralizing agent.

In a particularly preferred embodiment as described above using sodium bicarbonate as a neutralizing agent in combination with citric acid as a buffering agent, the molar ratio of sodium bicarbonate neutralizing agent to citric acid buffering agent is preferably about 4:1. Such formulations typically include from about 1000 to about 2000 mg (e.g., about 1250 mg, 1500 mg or 1700 mg) of sodium bicarbonate will contain from about 600 mg to about 1200 mg (e.g., about 750 mg, 900 mg or about 1000 mg) with about 1700 mg sodium bicarbonate and about 1000 mg citric acid comprising a preferred composition.

E. Anti-Hypotensive Agent

When the composition or kit comprises an anti-hypotensive agent (e.g., a tricyclic anti-depressant compound selected from the group consisting of protriptyline, mazindol, amitriptyline, nortriptyline, and desipramine), the anti-hypotensive agent is preferably administered as a subtherapeutic dose relative to conventional dosages known to those of ordinary skill in the art. Such subtherapeutic doses of the anti-hypotensive agent in general are preferably from about 0.2 to 30 mg/day (in divided doses) for an average-size human. This preferred dosage, however, varies with the anti-hypotensive agent selected. For example, when administered to an average-size human, it is preferred to use from about 2.0 to about 20 mg/dose for protriptyline for an average-size human, from about 0.2 to about 10 mg/dose for mazindol for an average-size human, from about 3.0 to about 30 mg/dose for amitriptyline for an average-size human, from about 2.0 to about 20 mg/dose for nortriptyline for an average-size human, and from about 2.0 to about 20 mg/dose for desipramine for an average-size human.

F. β-Receptor Blocker

When the composition or kit comprises a 1-receptor blocker (e.g., propranolol, atenolol, esmolol, metoprolol, labetalol, talinolol, timolol, carvedilol, or acebutolol), the β-receptor blocker is preferably administered as a subtherapeutic dose relative to conventional β-blocking dosages known to those of ordinary skill in the art. Such subtherapeutic doses of the β-receptor blocker typically vary with the compound selected. For example, the following dosages are preferred for the following compounds: from about 0.05 to about 0.2 mg of propranolol per kg body weight for an average-size human; from about 0.25 to about 0.1 mg of atenolol per kg body weight for an average-size human; from about 20 to about 300 μg of esmolol per kg body weight for an average-size human; from about 0.035 to about 0.1 mg of metoprolol per kg body weight for an average-size human; from about 100 to about 350 mg of labetalal per kg body weight for an average-size human; from about 350 to about 500 mg of talinolol per kg body weight for an average-size human; from about 300 to about 750 mg of timolol per kg body weight for an average-size human; and form about 50 to about 100 mg of acebutolol per kg body weight for an average-size human.

Methods of Use

As discussed above, the present invention is directed to preventing and treating cardiovascular conditions. The method comprises administering (orally or otherwise) a therapeutically-effective amount of one or more of the compositions or kits described above to a subject having or susceptible to such a condition.

Initial treatment of a patient suffering from a medical condition where treatment with the bretylium cation is appropriate can begin with the dosages discussed above. In many instances, the treatment is continued as necessary over a period of several weeks to several months or years until the condition has been controlled or eliminated. Patients undergoing treatment with the compositions or kits disclosed herein can be routinely monitored by any of the methods well known in the art to determine the effectiveness of therapy (e.g., by monitoring the prolongation of the QT_(c) interval in the electrocardiogram, etc.). Continuous analysis of such data permits modification of the treatment regimen during therapy so that optimal effective amounts of the compositions and kits of this invention may be administered at any point in time, and so that the duration of treatment can be determined as well. In this way, the treatment regimen and dosing schedule can be rationally modified over the course of therapy so that the lowest amount of the bretylium cation exhibiting satisfactory effectiveness is administered, and so that administration is continued only so long as is necessary to successfully prevent or treat the condition.

In accordance with the present invention, it has been discovered that the amount of the bretylium cation absorbed and/or the rate of absorption of the bretylium cation from the gastrointestinal tract (particularly the intestine) into the blood (i.e., the blood plasma or otherwise) and from the blood into the target cells can generally be improved by administering the bretylium cation (in a pharmaceutically acceptable source of the bretylium cation such as bretylium tosylate) to a subject, along with at least one source of lipophilic or weakly hydrophilic anion (i.e., a facilitating anion), and, optionally: (i) one or more neutralizing agents (e.g., sodium bicarbonate or sodium citrate) capable of temporarily increasing the pH of the aqueous contents in the stomach, (ii) one or more anti-hypotensive agents (e.g., protriptyline), (iii) one or more buffering agents (e.g., citric acid), and/or (iv) one or more β-receptor blockers (e.g., propranolol, esmolol, and/or metoprolol). This, in turn, generally provides improved bretylium cation concentrations in the blood (and, particularly, in the myocardium) and consequent improved bretylium cation AUC (area under the curve) values for at least about 30 minutes (more preferably at least about 2 hours, even more preferably at least about 6 hours, still even more preferably at least about 12 hours, and most preferably at least about 24 hours) following oral administration relative to the conventionally-tried oral compositions (particularly unformulated bretylium tosylate), and ultimately provides an improved efficacy of the bretylium cation administered to a subject in need thereof.

Biological membranes are lipid in character, as are nerve fibers. The bretylium ions must reach the nerve sites in order to be effective, i.e., they must pass from the blood, across the nerve blood barrier to the nerve fibers. If ingested orally, the bretylium ions must pass through the lipid mucosa of the intestine to reach the bloodstream, and from there, be distributed to the nerve fibers.

Several methods can be used to transfer the bretylium. In accordance with the preferred method, bretylium bromide is formulated with a pharmaceutically acceptable alkali metal or alkaline earth salt of a much less hydrophilic anion than bromide. The salt is then placed in a preparation that allows for oral ingestion. Upon oral ingestion, the salts dissolve in the stomach and the facilitating anion of the invention allows for greater uptake in the small intestine.

Alternatively, it is contemplated that salts of the bretylium cation and a non-facilitating anion could be ingested along with a salt of a non-quaternary ammonium cation (e.g., sodium, potassium, calcium or magnesium) and a facilitating anion. These salts could be combined together in a composition or alternatively be made available in a kit. The bretylium cation and the facilitating anion associate in the stomach upon mixing without absorption in the stomach to allow uptake in the small intestine.

It is further contemplated that any of the above methods (compounds or kits) could include the use of neutralizing agents, buffering agents, anti-hypotensive agents and/or β-receptor blockers or bethanidine sulfate. Such reagents could be incorporated into the compound or added into the kit. Use of neutralizing agents and buffers would increase the stomach pH to from about 2 to 7 to allow furthered uptake. Use of anti-hypotensive agents would tend to counteract the side effects of the bretylium compounds (which tend to cause orthostatic hypotension). Use of β-receptor blockers or bethanidine sulfate with bretylium enhances the effects of the bretylium on the patient in a synergistic effect.

For example, in accordance with the present invention, it has been discovered that the use of a bretylium cation with an acetylsalicylate anion (i.e., acetylsalicylic acid or an alkali metal salt thereof) and a β-receptor blocker (e.g., propranolol, esmolol, metoprolol, etc.) can significantly increase the electrical ventricular fibrillation threshold (VFT) in a subject (as measured by application of an electrical current, for example, as described in Example 15 below). Specifically, it has been found that upon orally administering a composition or kit of the present invention comprising a bretylium cation, an acetylsalicylate anion and a β-receptor blocker to a subject, the electrical ventricular fibrillation threshold measured in the subject about five minutes after administration of the composition or the components of the kit is at least about 25% higher (e.g., about 35%, 50%, 60%, 75%, 90% or 100% higher) than the electrical ventricular fibrillation threshold measured in the subject prior to the administration of the pharmaceutical composition or the components of the pharmaceutical kit. Further, the electrical ventricular fibrillation threshold measured in the subject about 30 minutes after the administration of a pharmaceutical composition or the components of a pharmaceutical kit comprising a bretylium cation, an acetylsalicylate anion and a β-receptor blocker is at least about two times higher (e.g., about three, four, five or six times higher) than the electrical ventricular fibrillation threshold measured in the subject before administration of the pharmaceutical composition or the components of the pharmaceutical kit.

It should also be understood that the invention contemplates the administration of the bretylium cations and the facilitating anions through compositions which contain mixtures of salts, i.e., a salt of the bretylium cation and a non-facilitating anion mixed with a salt of a non-quaternary ammonium cation and a facilitating anion. Such a composition could be ingested and allow the ions of interest to combine within the stomach and small intestine. Such mixtures would optionally include the use of other components such as neutralizing agents, buffering agents, anti-hypotensive agents and/or β-receptor blockers and/or bethanidine sulfate.

Suitable facilitating anions have aqueous to organic partition coefficients substantially larger than that of chloride ion or bromide ion. Examples include alkyl sulfates, alkyl sulfonates, monoalkyl and dialkyl phosphates, o-acyl salicylates, C-alkylsalicylates, and salicylate ion itself. The aqueous to organic partition coefficients measure the distribution ratio of the bretylium cation between an octanol-rich liquid phase and the aqueous-rich phase.

To measure the partition coefficient for a facilitating anion in the presence of a bretylium compound, an acidified aqueous solution of the bretylium compound with a non-facilitating anion (e.g., tosylate, bromide or chloride) is first prepared. Sodium bicarbonate and a salt comprising the facilitating anion to be tested are then added to the aqueous solution. The salt comprising the facilitating anion should be added in an amount sufficient to provide about a 1:1 molar ratio of the facilitating anion to the bretylium cation. The sodium bicarbonate is provided in an amount sufficient to produce a preselected pH value. An equal volume of n-octanol is then added to this solution. The solution is shaken. The mixture is centrifuged to separate an octanol-rich layer and an aqueous-rich layer, and the distribution ratio of the bretylium cation between the octanol-rich phase and the aqueous-rich phase (that is, the partition coefficient) may be measured. This analytical approach is believed to provide a suitable model for evaluating the bioavailability of the bretylium cation when utilized with a facilitating anion.

A. Order of Administration of the Bretylium Cation, the Facilitating Anion or β-Receptor Blocker, and Other Optional Ingredients of a Kit

As noted above, a kit may be used in accordance with this invention, wherein the therapeutic ingredients to be administered are contained in at least two separate, discrete sources. To illustrate, the source of the bretylium cation may be separate and discrete from the source of the facilitating anion and/or the source of the β-receptor blocker. Or, to illustrate further, the source of the bretylium cation may also contain the facilitating anion, while the neutralizing agent is contained in a separate, discrete source. Or to illustrate even further, the kits of the present invention may comprise two separate, discrete sources of ingredients which each contain a bretylium cation and a facilitating anion. Regardless, the use of a kit provides the advantage of being able to administer two or more different ingredients independently of each other. This, in turn, permits, for example, more effective adjustment in the amount of the facilitating anion, β-receptor blocker, neutralizing agent, buffering agent, and/or anti-hypotensive agent administered relative to the amount of the bretylium cation administered.

Typically, when a kit is used, it is preferred that the facilitating anion(s) and/or β-receptor blocker(s) (as well as any neutralizing agent, buffering agent, and/or anti-hypotensive agent) be administered jointly or within about 30 minutes before or after (and more preferably within about 15 minutes before or after) the bretylium cation is administered. An ingredient administered jointly with the bretylium cation may be administered as a component of a bretylium cation source (i.e., where the bretylium cation source is a composition containing the cation and the additional ingredient). Alternatively, the additional ingredient may be administered as a component of a source separate and distinct from the bretylium cation source (i.e., where the source of the additional ingredient is administered simultaneously with the cation source). Or, as another alternative, the source containing the additional ingredient may be combined with the bretylium cation source before the administration of the cation source, and thereby administered as a composition containing the bretylium cation and the additional ingredient.

In a particularly preferred embodiment, a kit is used which contains a source comprising a unit dosage of the bretylium cation and a separate source comprising a unit dosage of a facilitating anion (e.g., a kit containing a tablet comprising sodium acetylsalicylate or acetylsalicylic acid and a tablet comprising bretylium tosylate). The kit may also contain one or more other ingredients (e.g., a neutralizing agent, a buffering agent, a antihypotensive agent, and/or a β-receptor blocker which may be a component of the source of the bretylium cation, a component of the source of the facilitating anion, and/or a component of a source separate from the sources of the bretylium cation and facilitating anion.

In yet another particularly preferred embodiment, a source containing a unit dosage of a neutralizing agent (and, optionally, a unit dosage of a buffering agent) is initially administered. This is then followed by the administration of a source(s) containing the bretylium cation and a facilitating anion.

In still another particularly preferred embodiment, administration of a source(s) of the bretylium cation and a facilitating anion is followed (preferably immediately) by the administration of a source(s) containing a unit dosage of an anti-hypotensive agent and/or a β-receptor blocker. Optionally, administration of the anti-hypotensive agent may be delayed until the patient is to be ambulated.

B. Injectable Compositions

As noted above, many of the compositions and kits of the present invention may be administered parenterally. In one particularly preferred embodiment of this invention, an injectable composition is used which comprises the bretylium cation and a facilitating anion (e.g., a salicylate anion or an acetylsalicylate anion). Such a composition is particularly useful for the emergency treatment of, for example, ventricular fibrillation or myocardial infarction.

In a particularly preferred embodiment, the injectable composition comprises (1) the bretylium cation, (2) a facilitating anion, (3) a β-receptor blocker such as propranolol, and (4) a tricyclic antidepressant to prevent sympathetic blockade and a material decrease in blood pressure. Suitable tricyclic antidepressants are discussed above in detail.

In another particularly preferred embodiment, the injectable composition comprises (1) the bretylium cation, (2) a facilitating anion, and (3) a β-receptor blocker. Here, the facilitating anion is preferably a salicylate or acetylsalicylate anion. In one of the most preferred embodiments, the injectable composition comprises: (1) the bretylium cation (preferably in the form of bretylium tosylate), (2) acetylsalicylic acid or an alkali metal salt of acetylsalicylic acid, and (3) a β-receptor blocker. In all these embodiments, the more preferred β-receptor blockers are esmolol, metoprolol, and propranolol, with metoprolol and propranolol being the most preferred.

Other Quaternary Ammonium Cations

The pharmaceutical compositions and kits of the present invention also are useful for the oral administration of other nonpeptide cationic therapeutic agents, particularly therapeutic agents comprising quaternary ammonium cations, in accordance with the compositions and kits discussed above. These pharmaceutical compositions and kits can be prepared as set forth in this application by replacing the bretylium cation with a comparable molar fraction of a cation of the desired cationic therapeutic agent, such as propyromazine.

Forms of Pharmaceutical Compositions for the Quaternary Ammonium Cation and Facilitating Anion(s)

The pharmaceutical compositions of the present invention described above may also comprise one or more non-toxic, pharmaceutically-acceptable carriers, excipients, and/or adjuvants (collectively referred to herein as “carrier materials”). The pharmaceutical compositions of the present invention may be adapted for administration by any suitable route by selection of appropriate carrier materials and a dosage of the quaternary ammonium cation effective for the intended treatment.

The techniques used to prepare the pharmaceutical compositions of this invention vary widely, and include the well known techniques of pharmacy for admixing the components of a medicine composition. In general, the compositions are prepared by uniformly and intimately admixing the active compounds (in the form of, for example, powders) with or without a liquid or finely divided solid carrier, or both, and then, if necessary, encapsulating or shaping the product. For example, a tablet may be prepared by compressing or molding a powder or granules of the compound, optionally with one or more accessory ingredients. Compressed tablets may be prepared by compressing, in a suitable machine, the compound in a free-flowing form, such as a powder or granules optionally mixed with a binding agent, lubricant, inert diluent, and/or surface active/dispersing agent(s). Molded tablets can be made by molding, in a suitable machine, the powdered compound moistened with an inert liquid diluent.

In a particularly preferred embodiment, the composition is intended to be administered orally. In this instance, the carrier material(s) may be solid and/or liquid. Preferably, such a composition is formulated as a unit-dose composition, i.e., the pharmaceutical composition contains a desired specific amount of the quaternary ammonium cation and the facilitating anion, and is in the form of, for example, a tablet (with or without a coating), a hard or soft capsule, a lozenge, a cachet, a dispensable powder, granules, a suspension, an elixir, a liquid, or any other form reasonably adapted for oral administration. Liquid dosage forms for oral administration include, for example, pharmaceutically acceptable emulsions, solutions, suspensions, syrups, aerosols and elixirs containing inert diluents commonly used in the art, such as water or gas. Such compositions may also comprise, for example, wetting agents; emulsifying and suspending agents; and sweetening, flavoring, and perfuming agents. An excellent source which discusses in detail methods for preparing oral compositions (both solid and liquid) is Pharmaceutical Dosage Forms: Tablets, Second Edition, Revised and Expanded, Vol. 1-3 (ed. by Lieberman, H. A., Lachman, L., & Schwartz, J. B., Marcel Dekker, Inc., 270 Madison Ave, New York, N.Y. 1989) and Pharmaceutical Dosage Forms: Disperse Systems, Vol. 1-2 (ed. by Lieberman, H. A., Rieger, M. M., & Banker, G. S., Marcel Dekker, Inc., 270 Madison Ave, New York, N.Y. 1989).

The following discussion describes some of the more typical types of carrier materials that may be used in accordance with this invention. It should be recognized, however, that other carrier materials (such as colorants, flavors, sweeteners, and preservatives) are known in the pharmaceutical art, and may be used in the preparation of the pharmaceutical compositions of the present invention.

A. Diluents

The pharmaceutical compositions of the present invention may optionally comprise one or more pharmaceutically-acceptable diluents. Examples of suitable diluents include, either individually or in combination: lactose USP; lactose USP, anhydrous; lactose USP, spray dried; starch USP; directly compressible starch; mannitol USP; sorbitol; dextrose monohydrate; microcrystalline cellulose NF; dibasic calcium phosphate dihydrate NF; sucrose-based diluents; confectioner's sugar; monobasic calcium sulfate monohydrate; calcium sulfate dihydrate NF; calcium lactate trihydrate granular NF; dextrates, NF (e.g., Emdex); Celutab; dextrose (e.g., Cerelose); inositol; hydrolyzed cereal solids such as the Maltrons and Mor-Rex; amylose; Rexcel; powdered cellulose (e.g., Elcema); calcium carbonate; glycine; bentonite; polyvinylpyrrolidone; and the like.

B. Disintegrants

The pharmaceutical compositions of the present invention may optionally comprise one or more pharmaceutically-acceptable disintegrants, particularly for tablet formulations. Examples of suitable disintegrants include, either individually or in combination: starches; sodium starch glycolate; clays (such as Veegum HV); celluloses and various modifications of celluloses (such as purified cellulose, methylcellulose and sodium carboxymethylcellulose, and carboxymethylcellulose); alginates; pregelatinized corn starches (such as National 1551 and National 1550); Crospovidone, USP NF; gums (such as agar, guar, locust bean, Karaya, pectin, tragacanth); and the like.

C. Binding Agents and Adhesives

The pharmaceutical compositions of the present invention may optionally contain one or more binding agents or adhesives, particularly for tablet formulations. Such a binding agent or adhesive preferably imparts sufficient cohesion to the powders to allow for normal processing, such as sizing, lubrication, compression and packaging, while also allowing the tablet to disintegrate and the composition to dissolve upon ingestion. Examples of suitable binding agents and adhesives include, either individually or in combination: acacia; tragacanth; sucrose; gelatin; glucose; starch; cellulose materials (e.g., methylcellulose and sodium carboxymethylcellulose (e.g., Tylose)); alginic acid and salts of alginic acid; magnesium aluminum silicate; polyethylene glycol; guar gum; polysaccharide acids; bentonites; polyvinylpyrrolidone; polymethacrylates; hydroxypropylmethylcellulose (HPMC); hydroxypropylcellulose (Klucel); ethylcellulose (Ethocel); pregelatinized starch (e.g., National 1511 and Starch 1500); and the like.

D. Wetting Agents

The pharmaceutical compositions of the present invention may optionally contain one or more pharmaceutically-acceptable wetting agents. Such wetting agents preferably maintain the bretylium cation, and, where desired, other ingredients of the composition in suspension, and improve the relative bioavailability of the pharmaceutical composition. Examples of suitable wetting agents include, either individually or in combination: oleic acid; glyceryl monostearate; sorbitan mono-oleate; sorbitan monolaurate; triethanolamine oleate; polyoxyethylene sorbitan mono-oleate; polyoxyethylene sorbitan monolaurate; sodium oleate; sodium lauryl sulfate; and the like.

E. Lubricants

The pharmaceutical compositions of the present invention may optionally contain one or more pharmaceutically-acceptable lubricants. The lubricant preferably (1) imparts a surface to the composition (e.g., in the form of a tablet or capsule) that allows simple removal of the composition from a mold, and/or (2) increases the ability of the components of the composition to be mixed evenly and readily. Examples of suitable lubricants include, either individually or in combination: glyceryl behapate (Compritol 888); stearates (magnesium, calcium, sodium); stearic acid; hydrogenated vegetable oils (e.g., Sterotex); talc; waxes; Stearowet; boric acid; sodium benzoate and sodium acetate; sodium fumarate; sodium chloride; DL-Leucine; polyethylene glycols (e.g., Carbowax 4000 and Carbowax 6000); sodium oleate; sodium benzoate; sodium acetate; sodium lauryl sulfate; magnesium lauryl sulfate; and the like.

F. Anti-Adherent Agents and Glidants

The pharmaceutical compositions of the present invention optionally may comprise one or more anti-adherent agents and/or glidants. Examples of suitable anti-adherents and glidants include, either individually or in combination: talc, corn starch, Cab-O-Sil, Syloid, DL-Leucine, sodium lauryl sulfate, metallic stearates, and the like.

G. Enteric Coatings

In a particularly preferred embodiment, the pharmaceutical composition is in an enteric form, i.e., the pharmaceutical composition comprises a coating which is resistant to degradation in the stomach, but will decompose in the intestinal tract. In such an instance, the pharmaceutical composition is typically in the form of a tablet or capsule. Enteric coating materials are well-known in the art. For example:

-   -   1. In U.S. Pat. No. 4,849,227, Cho describes enteric coatings         containing: hydroxypropyl methylcellulose phthalate,         polyethylene glycol-6000, and/or shellac.     -   2. In U.S. Pat. No. 5,814,336, Kelm et al. describe polymer         enteric coatings having a thickness of at least about 250 μm,         and containing a polyanionic polymer that is insoluble in water         and aqueous solutions having a pH of less than about 5 to about         6.3. Examples of coating materials that Kelm et al. report to be         suitable are cellulose acetate phthalate, cellulose acetate         trimelliate, hydroxypropyl methylcellulose phthalate,         hydroxypropyl methyl cellulose acetate succinate, polyvinyl         acetate phthalate, poly(methacrylic acid, methyl methacrylate)         1:1, poly(methacrylic acid, ethyl acrylate) 1:1, and compatible         mixtures thereof.     -   3. In U.S. Pat. No. 5,914,132, Kelm et al. disclose a         multilayered polymer enteric coating to prevent the release of         an active ingredient until near the junction between the small         intestine and the colon (or while in the colon). This         multilayered coating has (1) an outer layer which has a         thickness of from about 20 to about 50 μm, and begins to         dissolve at a pH of between about 6.8 and about 7.2; and (2) an         inner layer which has a thickness of roughly from about 90 to         about 300 μm, and begins to dissolve at a pH of between about 5         and 6.3. Examples of coating materials that Kelm et al. report         to be suitable for the outer coating are poly(methacrylic acid,         methyl methacrylate) 1:2, and mixtures of poly(methacrylic acid,         methyl methacrylate) 1:1 and poly(methacrylic acid, methyl         methacrylate) 1:2 in a ratio of about 1:10 to about 1:2.         Examples of coating materials that Kelm et al. report to be         suitable for the inner coating are the same as those described         as being suitable coatings in U.S. Pat. No. 5,814,336.     -   4. In U.S. Pat. No. 5,733,575, Mehra et al. describe enteric         coatings made of titanized polyvinyl acetate phthalate,         polyvinyl acetate phthalate which has been jet milled,         hydroxypropyl methylcellulose phthalate, hydroxypropyl         methylcellulose acetate succinate, or cellulose acetate         phthalate.         See also, e.g., Shaffer et al., U.S. Pat. No. 4,147,768;         Maruyama et al., U.S. Pat. No. 5,750,148; Kukubo et al., U.S.         Pat. No. 5,776,501; and Gardner et al., U.S. Pat. No. 5,980,951.         H. Injectable Compositions

The compositions of this invention are generally not limited to being used orally. In general, they also may be administered by injection (intravenous, intramuscular, subcutaneous, or jet) if desired. Such injectable compositions may employ, for example, saline, dextrose, or water as a suitable carrier material. The pH of the composition may be adjusted, if necessary, with a suitable acid, base, or buffer. Suitable bulking, dispersing, wetting, or suspending agents (e.g., mannitol and polyethylene glycol (such as PEG 400)), may also be included in the composition. A suitable parenteral composition can also include eplerenone in injection vials. Aqueous solutions can be added to dissolve the composition before injection. The compositions of this invention may also be contained in pre-filled syringes for emergency use.

An excellent source which discusses in detail methods for preparing injectable compositions is Pharmaceutical Dosage Forms: Parenteral Medications, Vol. 1-2 (ed. by Avis, K. E., Lachman, L., & Lieberman, H. A., Marcel Dekker, Inc., 270 Madison Ave, New York, N.Y. 1989).

I. Resuscitation Solutions

In an especially preferred embodiment, the compositions of the present invention are in the form of a resuscitation solution suitable for administration to a patient suffering from atrial fibrillation or sudden cardiac arrest. Generally, such resuscitation solution compositions comprise a salt of bretylium, acetylsalicylic acid or an alkali metal salt of acetylsalicylic acid, a β-receptor blocker and a neutralizing agent dissolved in an aqueous carrier such as an aqueous solution of 5% glucose. For example, in a preferred composition, the resuscitation solution comprises bretylium tosylate, acetylsalicylic acid, propranolol and methyl glucamine (i.e., meglumine). In an alternative preferred composition, the resuscitation solution comprises bretylium tosylate, acetylsalicylic acid, metoprolol and methyl glucamine. Optionally, the resuscitation solution compositions may further comprise an anti-hypotensive agent such as epinephrine or methomamine and/or compounds such as V74389G or V74006F, which may protect the brain by preventing lipid peroxidation during atrial fibrillation.

Preferred dosages for the resuscitation solution compositions comprise from about 5 mg/kg to about 20 mg/kg bretylium ion (preferably about 15 mg/kg bretylium ion); from about 2.5 mg/kg to about 10 mg/kg acetylsalicylic acid (preferably about 7.5 mg/kg acetylsalicylic acid); and from about 0.25 mg/kg to about 2 mg/kg of a β-receptor blocker (preferably 1 mg/kg for propranol, 0.5 mg/kg for metoprolol and 0.5 ug/kg for esmolol). Optionally, the dosages may further comprise from about 0.2 meq/kg to about 0.4 meq/kg (preferably 0.3 meq/kg) of an amino sugar neutralizing agents such as methyl glucamine, i.e. meglumine; from about 0.19 ug/kg to about 1 mg/kg, preferably 0.3 mg/kg of an anti-hypotensive agent such as epinephrine; from about 0.1 mg/kg to about 0.3 mg/kg, preferably 0.2 mg/kg of V74389G; and/or from about 0.1 mg/kg to about 0.3 mg/kg, preferably 0.3 mg/kg of V74389G. For example, in a preferred resuscitation solution, the composition of the present invention comprises bretylium tosylate (15 mg/kg) and acetylsalicylic acid (7.5 mg/kg) with propranolol (1 mg/kg) or metoprolol (0.5 mg/kg) and/or epinephrine (0.2 mg/kg), V74309G (0.3 mg/kg) or V74006F (0.3 mg/kg).

The resuscitation solution compositions described above are useful in treating patients suffering from atrial fibrillation. For example, it has been found that administering such a resuscitation solution either alone or in combination with conventionally used thrombolitic therapies for converting atrial fibrillation to sinus rhythm (most notably, shocking the chest wall or implantation of an atrial defibrillator) to a patient suffering from atrial fibrillation can help return a patient to normal sinus rhythm. Preferably, it is desired to administer the resuscitation solution to a patient immediately upon suffering atrial fibrillation. However, when the resuscitation solution is administered to a patient in coordination with another thrombolitic thereapy or an external defibrillatory shock, it is preferred to administer the resuscitation solution composition to the patient prior to the administration of the thrombolitic therapy or before a first defibrillatory shock. Alternatively, the resuscitation solution may be administered immediately following a first defibrillatory shock. When used with an external shock, the resuscitation solution may be administered at any time before or after the defibrillatory shock, including from about five minutes (e.g., 5, 4, 3, 2 or 1 minute) to about 30 seconds before a defibrillatory shock to about five minutes (e.g., 5, 4, 3, 2, 1 minute) to about 30 seconds or immediately after shocking the chest wall. Further, when used in combination with an external defibrillatory shock, it has been found that administering the resuscitation solution compositions (either orally or parenterally) to a patient suffering from atrial fibrillation prior to shocking the chest wall can reduce and/or prevent aortic trauma normally associated external defibrillation.

Preparation of Bretylium Salts with Hydrophobic or Weakly Hydrophilic Anions

Further in accordance with the invention, an advantageous process is provided for producing a salt of a bretylium cation and a relatively hydrophobic anion, i.e., more hydrophobic than a halide ion or a tosylate anion. In this process, an aqueous solution of a mineral acid salt of the bretylium cation is mixed with a source of alkali metal or alkaline earth metal salt of said anion. The resulting mixture is then contacted with a substantially water-immiscible organic solvent, thereby transferring the relatively hydrophobic salt of the bretylium cation and the more hydrophobic anion to the solvent phase and producing an organic extract comprising the transferred salt. An alkaline or alkaline earth salt of the mineral acid remains in the raffinate phase.

Preparation of Bretylium Halide

A bretylium halide salt, e.g., 2-bromobenzylethyl-dimethylammonium bromide, may conveniently be prepared by reaction of 2-bromobenzyl halide with ethyldimethylamine in the presence of water. In this process, 2-bromobenzylbromide is mixed with water, preferably in a ratio of between about 0.1 and 2 moles, more preferably between about 0.3 and about 1.6 moles, most preferably between about 0.9 and about 1.1 moles of 2-benzylbromide per liter of water. A two phase liquid mixture is obtained. Ethyldimethylamine is added to the mixture, preferably in small incremental portions, and preferably up to a total of between about 2 and about 6 moles ethyldimethylamine per mole of 2-bromobenylbromide, more preferably in a ratio of 3 to 5 moles, most preferably in a range of 3.5 to 4.5 moles, per mole 2-bromobenzylbromide. Ethyldimethylamine serves both as reactant and buffer for the reaction. To provide further control of the pH, a mineral acid such as HCl is added to the reaction mixture during the reaction. The reaction pH is preferably maintained between 8.5 and 10.5, more preferably between 9 and 10, most preferably between 9.5 and 10. Between 30 minutes and 90 minutes after addition of the amine is complete, the reaction mixture becomes a homogeneous solution containing bretylium bromide, excess ethyldimethylamine, ethyldimethylammonium salts, e.g., ethyldimethylammonium bromide and ethyldimethylammonium chloride, and water. It may also contain small amounts of 2-bromobenzyl alcohol and unreacted 2-bromobenzyl bromide.

Preparation of Bretylium Salt of Interest

Ethyldimethylamine and most of the water is removed from the reaction mixture by evaporation under vacuum. A concentrated aqueous solution of bretylium bromide and chloride is left behind, as the bretylium salts are nonvolatile.

An alkali metal salt of the hydrophobic or weakly hydrophilic anion, (e.g. sodium dodecylsulfate, sodium lauryl sulfate, potassium salicylate or potassium di(2-ethylhexyl)sulfosuccinate) is added to the concentrated solution of bretylium salts, along with a water-immiscible organic solvent, e.g., chloroform (or any equivalent, such as methylene chloride or diethylether), and a minimum amount of distilled water necessary to facilitate isolation of the quaternary ammonium salt of the more hydrophobic anion by transfer of salts between aqueous and organic phases. Preferably, from 0.5 to 2.0 moles of the hydrophobic anion are added per mole of bretylium salt, more preferably from 0.8 to 1.5 moles of the hydrophobic anion are added, and most preferably from 1.1 to the anion is added.

Preferably, water is added in a ratio from about zero to two times the weight of the concentrated solution of the bretylium salts, more preferably from 0.5 to 1.5 times and most preferably from 0.8 to 1.2 times. Preferably, the organic extractant, e.g., chloroform, is added in a proportion from 3 to 30 times the weight of the concentrated solution of bretylium salts, more preferably from 5 to 20 times, and most preferably from 8 to 12 times the weight of the concentrated bretylium salts.

A two phase liquid-liquid mixture results. The mixture is agitated vigorously and then allowed to separate. The bretylium salt of interest concentrates in the chloroform phase and the alkali metal halide concentrates in the aqueous phase. Partition coefficients in such a system, defined as [bretylium(aqueous)]/[bretylium(chloroform)], are conservatively estimated to be about greater than 10.

The water phase is decanted off the organic extract phase. A high volatility solvent such as chloroform may be evaporated at a pressure of about one torr for 24 hours at room temperature. Next, the temperature is increased, e.g., to 43 degrees Celsius in the case of chloroform, and the evaporation is continued for about another hour. Other pressures and lengths of time may be used by those skilled in the art without overheating the product to remove the solvent. The residue which contains the product is a very viscous, colorless cloudy liquid.

The purity of the salt can be determined spectrophotometrically. Preferably yields should be greater than 50%, more preferably greater than 70% and most preferably greater than 85%.

Definitions

The term “hydrocarbyl” refers to a group composed of carbon and hydrogen. This definition includes alkyl, alkenyl, and alkynyl groups which are each straight chain, branched chain, or cyclic hydrocarbons typically having from 1 to about 30 carbons atoms. Also included in this definition are aryl groups composed of carbon and hydrogen. Hydrocarbyl therefore includes, for example, methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, methylcyclopentyl, ethenyl, propenyl, butenyl, pentenyl, hexenyl, ethyne, propyne, butyne, pentyne, hexyne, phenyl, naphthyl, anthracenyl, benzyl, and isomers thereof.

The term “substituted hydrocarbyl” refers to a hydrocarbyl group in which one or more hydrogen has been substituted with a heteroatom-containing group. Such substituent groups include, for example, halo, oxo, heterocycle, alkoxy, hydroxy, aryloxy, —NO₂, amino, alkylamino, or amido. When the substituent group is oxo, the substituted hydrocarbyl can be, for example, an acyl group.

The term “alkyl” refers to linear or branched hydrocarbon groups having from 1 to about 30 carbon atoms. Examples of such groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, iso-amyl, hexyl, dodecyl, and the like. It should be recognized that such a group may be, for example, a residue of a saturated fatty acid formed by removing the carboxylic acid group from the fatty acid. More preferred alkyl groups are alkyl groups comprising at least 6 carbon atoms.

The term “alkenyl” embraces linear or branched hydrocarbon groups having at least one carbon-carbon double bond, and from 2 to about 30 carbon atoms. Examples of alkenyl groups include ethenyl, allyl, propenyl, butenyl, 4-methylbutenyl, and the like. The term “alkenyl” embraces groups having “cis” and “trans” orientations, or, alternatively, “E” and “Z” orientations. It should be recognized that such a group may be, for example, a residue of an unsaturated fatty acid (having one or more double carbon-carbon bonds) formed by removing the carboxylic acid group from the fatty acid. More preferred alkenyl groups are alkyl groups comprising at least 6 carbon atoms.

The term “alkynyl” refers to linear or branched hydrocarbon groups having at least 1 carbon-carbon triple bond, and from 2 to about 30 carbon atoms. Examples of alkynyl groups include propargyl, 1-propynyl, 2-propynyl, 1-butyne, 2-butynyl, 1-pentynyl, and the like. More preferred alkyl groups are alkynyl groups comprising at least 6 carbon atoms.

The term “cycloalkyl” refers to saturated carbocyclic hydrocarbon groups having 3 to about 30 carbon atoms. Examples of such groups include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, and the like. More preferred cycloalkyl groups are “lower cycloalkyl” groups having from 3 to about 8 carbon atoms.

The term “cycloalkenyl” refers to partially unsaturated carbocyclic hydrocarbon groups having from 3 to about 30 carbon atoms. Examples of such groups include cyclobutenyl, cyclopentenyl, cyclohexenyl, and the like. More preferred cycloalkenyl groups are “lower cycloalkenyl” groups having from 4 to about 8 carbon atoms.

The term “aryl” refers to aromatic groups such as phenyl, naphthyl, tetrahydronaphthyl, indanyl, and biphenyl. The preferred aryl is phenyl. Aryl moieties may also be substituted at a substitutable position with one or more substituents selected independently from alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, and the like. The term “aryl, alone or in combination” refers to a carbocyclic aromatic system containing 1, 2, or 3 rings, wherein such rings may be attached together in a pendent manner or may be fused.

The term “arylalkyl” refers to aryl-substituted alkyl groups such as benzyl, diphenylmethyl, triphenylmethyl, phenylethyl, and diphenylethyl. The aryl in the aralkyl may be additionally substituted with one or more substituents selected independently from alkyl, alkenyl, alkynyl, cycloalkyl, and cycloalkenyl. The terms “arylalkenyl” and “arylalkynyl” are defined in a comparable manner.

The term “pharmaceutically acceptable” means being compatible with the other components of the composition or kit being administered, and not deleterious to the intended recipient of the composition or kit.

The term “pharmaceutically-acceptable salts” refers to salts such as alkali metal salts, and common salts of free acids or free bases. The nature of the salt is not critical, provided that it is pharmaceutically-acceptable. Suitable pharmaceutically-acceptable salts of the bretylium cation and/or facilitating anion may be prepared from an inorganic acid or an organic acid. Examples of such inorganic acids are hydrochloric, hydrobromic, hydroiodic, nitric, carbonic, sulfuric, and phosphoric acid. Appropriate organic acids may be selected from aliphatic, cycloaliphatic, aromatic, araliphatic, heterocyclyl, carboxylic, and sulfonic classes of organic acids (e.g., formic, acetic, propionic, succinic, glycolic, gluconic, lactic, malic, tartaric, citric, ascorbic, glucuronic, maleic, fumaric, pyruvic, aspartic, glutamic, benzoic, anthranilic, mesylic, stearic, salicylic, p-hydroxybenzoic, phenylacetic, mandelic, embonic (pamoic), methanesulfonic, ethanesulfonic, benzenesulfonic, pantothenic, toluenesulfonic, 2-hydroxyethanesulfonic, sulfanilic, cyclohexylaminosulfonic, algenic, β-hydroxybutyric, galactaric, and galacturonic acid). Suitable pharmaceutically-acceptable salts of these compounds include metallic salts and organic salts. More preferred metallic salts include, but are not limited to, appropriate alkali metal (group IA) salts, alkaline earth metal (group IIA) salts, and other physiologically acceptable metals. Such salts can be made from aluminum, calcium, lithium, magnesium, potassium, and sodium. Preferred organic salts can be made from amines and quaternary ammonium salts, including, in part, trimethylamine, diethylamine, N,N′-dibenzylethylenediamine, chloroprocaine, choline, diethanolamine, ethylenediamine, meglumine (N-methylglucamine), and procaine.

The term “ventricular fibrillation threshold” refers to the lowest current level that, when applied to the heart, causes sustained ventricular fibrillation.

The term “effective ventricular refractory period” refers to the period during which the heart cannot be stimulated to contract by a super threshold electrical stimulus.

The term “rate-corrected Q-T_(c) interval” refers to the interval between the Q wave and the T wave, corrected for heart rate.

The term “prevent” means to at least partially suppress the onset of a condition.

With reference to the use of the word(s) “comprise” or “comprises” or “comprising” in this entire specification (including the claims below), Applicants note that unless the context requires otherwise, those words are used on the basis and clear understanding that they are to be interpreted inclusively, rather than exclusively, and that Applicants intend each of those words to be so interpreted in construing this entire specification.

EXAMPLES

The following examples are simply intended to further illustrate and explain the present invention. This invention, therefore, should not be limited to any of the details in these examples. The symbols and conventions used in these examples are consistent with those used in the contemporary pharmacological literature.

Unless otherwise stated, the pharmaceutical grade bretylium tosylate used in these examples was obtained from Ganes Chemicals, Inc., Carlstadt, N.J. The facilitating anions used in these examples are commercially available or may be prepared as discussed above.

Example 1

A pharmaceutical composition suitable for oral administration was prepared having the following composition:

INGREDIENT WEIGHT PERCENT¹ bretylium cations 0.5% to 50% facilitating anions 0.5% to 50% neutralizing agent  15% to 99% ¹Based on the total weight of the bretylium cations, facilitating anions, and neutralizing agent.

Example 2

A pharmaceutical composition suitable for oral administration was prepared having the following composition:

INGREDIENT WEIGHT PERCENT¹ bretylium cations   1% to 30% facilitating anions 1.7% to 30% neutralizing agent  50% to 98% ¹Based on the total weight of the bretylium cations, facilitating anions, and neutralizing agent.

Example 3

A pharmaceutical composition suitable for oral administration was prepared having the following composition:

AMOUNT INGREDIENT (mg) WEIGHT FRACTION¹ bretylium tosylate 500 0.095 (0.056 for bretylium cation alone) sodium di(2-ethylhexyl) 536 0.102 sulfosuccinate (0.097 for di(2-ethylhexyl) sulfosuccinate anion alone) sodium bicarbonate 4200  0.802 ¹Based on the total weight of the composition.

Example 4

A pharmaceutical composition suitable for oral administration was prepared having the following composition:

AMOUNT INGREDIENT (mg) WEIGHT FRACTION¹ bretylium tosylate 1275 0.275 (0.161 for bretylium cation alone) sodium di(2-ethylhexyl) 1367 0.294 sulfosuccinate (0.279 for di(2-ethylhexyl) sulfosuccinate anion alone) sodium bicarbonate 2000 0.431 ¹Based on the total weight of the composition.

Example 5

A pharmaceutical composition suitable for oral administration was prepared having the following composition:

AMOUNT INGREDIENT (mg) WEIGHT FRACTION¹ bretylium tosylate 1275 0.214 (0.126 for bretylium cation alone) sodium salicylate  485 0.081 (0.069 for salicylate anion alone) sodium bicarbonate 4200 0.705 ¹Based on the total weight of the composition.

Example 6

A pharmaceutical composition suitable for oral administration was prepared having the following composition:

AMOUNT INGREDIENT (mg) WEIGHT FRACTION¹ bretylium di(2-ethyl- 3600 0.643 hexyl)sulfosuccinate (0.235 for bretylium cation alone) (0.408 for di(2-ethylhexyl) sulfosuccinate anion alone) sodium bicarbonate 2000 0.357 ¹Based on the total weight of the composition.

Example 7

A pharmaceutical composition suitable for oral administration was prepared having the following composition:

AMOUNT INGREDIENT (mg) WEIGHT FRACTION¹ bretylium di(ethylhexyl) 3600 0.545 sulfosuccinate (0.2 for bretylium cation alone) (0.345 for di(2-ethylhexyl) sulfosuccinate anion alone) sodium bicarbonate 2000 0.303 citric acid 1000 0.152 ¹Based on the total weight of the composition.

Example 8

A pharmaceutical composition suitable for oral administration was prepared having the following composition:

AMOUNT INGREDIENT (mg) WEIGHT FRACTION¹ bretylium salicylate 2000 0.4 (0.241 for bretylium cation alone) (0.159 for salicylate anion alone) sodium bicarbonate 2000 0.4 citric acid 1000 0.2 ¹Based on the total weight of the composition.

Example 9

A pharmaceutical composition suitable for oral administration was prepared having the following composition:

AMOUNT INGREDIENT (mg) WEIGHT FRACTION¹ bretylium tosylate 120 0.261 (0.153 for bretylium cation alone) sodium di(2-ethylhexyl)- 130 0.283 sulfosuccinate (0.268 for di(2-ethylhexyl)- sulfosuccinate anion alone) sodium citrate 200 0.435 protriptyline  10 0.022 ¹Based on the total weight of the composition.

Example 10

A pharmaceutical composition was prepared having the following composition:

AMOUNT INGREDIENT (mg) WEIGHT FRACTION¹ bretylium tosylate 12,000 0.021 (0.012 for bretylium cation alone) aspirin  5,000 0.009 (0.008 for acetylsalicylate anion alone) sodium citrate 50,000 0.088 water 500,000  0.882 (500 ml) ¹Based on the total weight of the composition.

Generally, sodium citrate is not necessary when administering this composition parenterally (e.g., by continuous infusion over an appropriate period). Alternatively, the composition can be further divided into suitable unit oral dosage forms (e.g., unit dosage forms containing 120 mg of bretylium tosylate), and orally administered.

Example 11

An oral pharmaceutical composition was prepared having the following composition:

WEIGHT INGREDIENT AMOUNT (mg) FRACTION¹ bretylium di(2-ethylhexyl)- 500 0.926 sulfosuccinate protriptyline  40 0.074 water An amount sufficient to provide a total final volume for the solution of 50 ml ¹Based on the total weight of bretylium di(2-ethylhexyl)sulfosuccinate and protriptyline.

Example 12

A pharmaceutical composition suitable for oral administration was prepared having the following composition:

INGREDIENT WEIGHT PERCENT¹ bretylium cations 0.5% to 64% facilitating anions 0.3% to 63% neutralizing agent 0.02% to 99%  ¹Based on the total weight of the bretylium cations, facilitating anions, and neutralizing agent.

Example 13 Determination of Partition Coefficients

Several formulations of the present invention were tested using an n-octanol/aqueous buffer system to measure the partition coefficients for the bretylium cation in the presence of the facilitating anions of those formulations. An acidified aqueous solution of bretylium tosylate was first prepared. Sodium bicarbonate and a salt comprising the facilitating anion to be tested was then added to the aqueous solution. The salt comprising the facilitating anion was added in an amount sufficient to provide a 1:1 molar ratio of the facilitating anion to the bretylium cation. The sodium bicarbonate was provided in an amount sufficient to produce one of 4 preselected pH values. An equal volume of n-octanol was then added to this solution and the solution was shaken. The mixture was centrifuged to separate an octanol layer and an aqueous layer, and the distribution ratio of the bretylium cation between the octanol-rich phase and the aqueous-rich phase (that is, the partition coefficient) was measured. This analytical approach provides a suitable model for evaluating the bioavailability of the bretylium cation in the compositions tested.

A. Preparation of Aqueous Bretylium Tosylate Solution

The aqueous bretylium tosylate solutions used in the procedure were prepared in the following manner. An amount of one of the buffer solutions described below (3.0 ml when the most acidic buffer solution was used, and 4.0 ml when the other 3 buffer solutions were used) was transferred to a beaker or an Erlenmeyer flask by pipette. To the buffer solution was added 50 mg of bretylium tosylate per ml of buffer solution and an equimolar amount of the sodium salt of the facilitating anion. For example, where the facilitating anion tested was di(2-ethylhexyl)sulfosuccinate, 54 mg of sodium di(2-ethylhexyl)sulfosuccinate was added per ml of buffer solution. Where the facilitating anion tested was salicylate, 19 mg of sodium salicylate was added per ml of buffer solution. Test solutions comprising other facilitating agents were prepared in a similar manner.

B. Preparation of Sodium Bicarbonate Buffer Solutions

Each of the pharmaceutical compositions was tested using each of the following sodium bicarbonate buffer systems:

The first buffer solution was prepared by dissolving 1.0 g of sodium bicarbonate in 100 ml of 0.95M HCl. A pH meter equipped with a conventional glass electrode and a calomel reference electrode was used to measure the nominal pH of this solution and the other 3 buffer solutions. The nominal pH measured for the first solution was 0.8. Because the glass electrode probably is not able to respond adequately to such an acidic solution, it is likely that the actual pH of this solution was lower, perhaps slightly negative. The nominal pH of this solution, however, was reproducible.

The second buffer solution was prepared by dissolving 7.5 g of sodium bicarbonate in 100 ml of 0.95M HCl. This solution had a reproducible nominal pH of 2.2, slightly higher than the expected pH of about 2.0.

The third buffer solution was prepared by dissolving 8.0 g of sodium bicarbonate in 100 ml of 0.95M HCl. This solution had a nominal pH between about 5.0 and about 6.0. While the pH meter is reliable in this pH range, the pH was somewhat variable because the solution had minimal buffer capacity.

The 4th buffer solution was prepared by dissolving 10.0 g of sodium bicarbonate in 100 ml of 0.95M HCl. This solution had a reproducible nominal pH of 7.7 that likely is close to the actual pH of the solution.

The first buffer solution was intended to model the acidity of the aqueous contents of the human stomach. The other 3 buffer solutions were intended to model the aqueous contents of the stomach after administration of an amount of sodium bicarbonate to reduce the acidity of the stomach.

C. Facilitating Anions Tested

The sodium salts of the following facilitating anions were tested: di(2-ethylhexyl)phosphate, di(2-ethylhexyl)sulfosuccinate, lauryl sulfate, and salicylate. All these salts were commercially available from Aldrich Chemical, Milwaukee, Wis. and/or Ecolab, Inc., St. Paul Minn. Each of the 4 facilitating anions was tested in each of the 4 buffer systems.

D. Preparation and Equilibration of n-Octanol/Buffer Systems

A 1.0 ml aliquot of the formulated aqueous test solution was added to 1.0 ml of n-octanol (Aldrich Chemical Co., HPLC grade, 99% purity), and the mixture was shaken for 30 seconds. The n-octanol and aqueous phases, which are not miscible, were separated by centrifuging at about 3000 rpm for about 10 minutes or until clarification was achieved. The phases were physically separated and the bretylium concentration of each phase was determined as described below. This procedure was followed for each combination of facilitating anion and buffer system. In addition, a corresponding control test was carried out without a facilitating anion in each of the buffer systems.

E. Measurement of Partition Coefficient

The concentration of the bretylium cation in the separated n-octanol and aqueous phases was determined by spectrophotometry using the long wavelength absorption of the bretylium cation at 270 nm. This band is due to the benzene chromophore of the bretylium cation.

To determine the concentration of bretylium in the octanol phase, each n-octanol phase sample obtained as above was diluted with an equal volume of pure n-octanol. The resulting n-octanol solution was then equilibrated with 1.5 times its own volume of 3 M HCl to protonate the acid of any acid weaker than HCl that was present. Because bretylium chloride is very water soluble but only sparingly soluble in n-octanol, it is extracted into the aqueous phase in high yield. The absorbance of the resulting aqueous phase at 270 nm was then determined spectrophotometrically. The protonated former facilitating anion (which otherwise might contribute to the absorbance) was converted to its neutral conjugate acid by the HCl and remained in the n-octanol phase. For example, if the bretylium cation is present as a tosylate in the octanol phase, then acidification largely converts the tosylate anion to toluenesulfonic acid, an acid preferentially soluble in the n-octanol phase. Accordingly, the facilitating anion is not transferred to the aqueous phase with the bretylium chloride and does not contribute to the measured absorbance. The chloride anion is present in the aqueous phase but is free of absorbance in the region of interest.

To determine the concentration of bretylium in the aqueous phase, each aqueous phase sample obtained as above was mixed with twice its own volume of 5M HCl and the resulting aqueous solution was then equilibrated with a volume of n-octanol equal to twice the original aqueous phase sample volume. The HCl protonated the facilitating anion and any other anions of acids weaker than HCl that were present and might contribute to the absorbance if allowed to remain in solution. The unwanted anions were extracted into the n-octanol phase as their conjugate acids. The absorbance of the aqueous phase, after the n-octanol extraction, was determined spectrophotometrically at 270 nm.

Test solutions exhibiting a measured absorbance greater than 1.2 were diluted with water so as to provide an absorbance between 0.040 and 1.2 and then re-measured. This dilution was employed to provide bretylium concentrations within the concentration range in which absorbance could be reliable measured. In such cases, the absorbance of the diluted test solution was then multiplied by a dilution factor to determine the true absorbance of the original test solution. Alternatively, the original separated aqueous solution and the corresponding original separated n-octanol solution were diluted by the same factor so as to cancel out the dilution factor during the calculation of the partition coefficient.

Dilution occurs whenever additional solvent is added to a solution of an analyte, or the analyte is transferred to a new solution of greater volume than its original volume. Such increases in volume may occur for reasons of convenience, or because the parameter to be measured (e.g., absorbance) is above the optimal range of instrumental accuracy. The dilution factor is the final volume divided by the initial volume. If several dilutions have been made the dilution factors are multiplicative. For example, if the original aqueous test sample was 1.0 ml (as in the present case) and the bretylium ion is recovered in 1.5 ml of aqueous acid, the dilution factor is 1.5. If the absorbance of this solution is too high for accurate measurement, and 0.3 ml of this solution is diluted with 5 ml of water, a second dilution has occurred with a dilution factor of 17.7 (that is, 5.3/.3). The overall dilution factor is 26.5 (that is, 17.7×1.5). To determine the absorbance of the original solution, which is proportional to its bretylium concentration, the absorbance of the final solution is multiplied by the overall dilution factor (26.5 in the illustrative example). The proportionality constant that converts absorbance to the molar concentration of the bretylium cation is the molar absorbance.

In the present case, the ratio of the bretylium concentration in the octanol phase to the bretylium concentration in the aqueous phase (i.e., the partition coefficient) is needed. When the 2 overall dilution factors are the same, then the ratio of concentrations is equal to the ratio of observed absorbances. When the 2 overall dilution factors are not the same, then the ratio of observed absorbances times the ratio of dilution factors equals the ratio of concentrations. The analytical scheme described above has the advantage that all absorbances are measured in aqueous solution, so that the molar absorbance is constant.

The partition coefficients calculated from the measured absorbances are set forth in Table 1A below. These test results confirm that the partition coefficient (and, thus, the bioavailability) of orally administered bretylium cations can be increased—in some cases up to nearly 10-fold—by using suitable a facilitating anion and/or a neutralizing agent in combination with the bretylium cation. While increasing the pH of the test solution alone increased partition coefficient values, increasing the pH of the solution in combination with the addition of a suitable facilitating anion resulted in an additional increase in partition coefficient values in all cases. Similarly, use of certain facilitating anions in combination with the bretylium cation without a concurrent increase in the pH of the test solution materially increased partition coefficient values, particularly for the sulfate and sulfosuccinate facilitating anions tested. The phosphate and salicylate facilitating anions tested, however, generally performed better and provided higher partition coefficient values as the pH of the test solution increased.

TABLE 1A PARTITION NOMINAL pH FACILITATING ANION COEFFICIENT 0.8 None 0.33 2.1 None 0.48 5.5 None 0.45 7.7 None 0.49 0.8 di(2-ethylhexyl)phosphate 0.35 2.2 di(2-ethylhexyl)phosphate 0.49 5.5 di(2-ethylhexyl)phosphate 0.51 7.7 di(2-ethylhexyl)phosphate 2.33 0.8 di(2-ethylhexyl)sulfosuccinate 2.19 2.2 di(2-ethylhexyl)sulfosuccinate 2.52 5.5 di(2-ethylhexyl)sulfosuccinate 4.16 7.7 di(2-ethylhexyl)sulfosuccinate 3.61 0.8 lauryl sulfate 1.91 2.2 lauryl sulfate 3.54 5.5 lauryl sulfate 3.71 7.0 lauryl sulfate 4.01 0.8 salicylate 0.56 2.2 salicylate 1.31 5.5 salicylate 1.31 7.0 salicylate 1.90 F. Control Experiments

Two series of control experiments were conducted to further validate the above procedure. In the first series of experiments, the molar absorbance of bretylium in the absence of a facilitating anion was measured at 2 different initial concentrations. Bretylium tosylate in an amount of 150 mg was added to 3.0 ml of water. This solution was then acidified with HCl, extracted with octanol, and diluted in accordance with the procedure described above. The experiment was repeated using an initial aqueous solution that was 100 times more dilute. The molar absorbance was calculated for each solution by dividing its absorbance after extraction by its initial concentration. The results are reported in Table 1B below.

TABLE 1B INITIAL BRETYLIUM MOLAR TOSYLATE ABSORBANCE CONCENTRATION (moles/L) ABSORBANCE¹ (L/mole) 1.21 × 10⁻¹ 43.0 355 1.21 × 10⁻³ 0.39 326 ¹Corrected for dilution

The consistency of the molar absorbance over 2 orders of magnitude of initial concentration shows that the measured absorbance, corrected for dilution, is proportional to the bretylium concentration, as indicated.

In the second series of experiments, the procedure was tested using a solution containing the salicylate facilitating anion, but not the bretylium cation. To the second buffer solution (prepared as described above) was added a sufficient amount of sodium salicylate and tetrabutylammonium bromide to provide a 0.21 M sodium salicylate/0.12 M tetrabutylammonium bromide solution. Tetrabutylammonium bromide was used as a phase transfer agent to mimic the bretylium cation and ensure the transfer of a substantial amount of salicylate anion to the n-octanol phase. The solution was divided into 3 portions of about 0.7 g each, and 1.0 g of n-octanol was added to each of the 3 solutions. The solutions were shaken for about 30 seconds and then centrifuged at about 3000 rpm for about 5 minutes to clarify both phases. About 0.7 g of each n-octanol phase was removed and weighed and an equal weight of 5 M HCl was added to each n-octanol sample. The new 2-phase systems were shaken (about 30 seconds), and separated by centrifugation (3000 rpm for about 5 minutes) to produce clear solutions. The absorbance of these solutions at 270 nm was measured. This procedure was also carried out using the third and 4th buffer solutions (prepared as described above). The results are disclosed in Table 1C below.

TABLE 1C FINAL AQUEOUS FINAL OCTANOL ORIGINAL pH ABSORBANCE ABSORBANCE 2.1 0.049 1.095 5.5 0.047 0.814 7.7 0.056 0.828

The sodium cation is nearly free of absorbance in the region of interest. Although the salicylate anion and salicylic acid absorb light in the ultraviolet region, they do not exhibit absorption maxima at or near the 270 nm absorption region of the bretylium cation. The results reported in Table 1C indicate that only about 5 to 6% of the salicylate anion/salicylic acid is transferred to the final aqueous HCl solutions. The absorbance at 270 nm resulting from the transferred salicylate anion/salicylic acid is not materially significant when compared to the absorbance measured for the bretylium cation using the procedure discussed above. The combination of minimal absorbance at 270 nm and the extraction of salicylic acid into the octanol phase ensures that salicylate does not materially interfere with the determination of the bretylium concentration in accordance with the procedure described above.

Example 14 Effect of Facilitating Anion Concentration on the Partition Coefficient

The procedure of Example 13 was repeated for the di(2-ethylhexyl)sulfosuccinate and salicylate facilitating anions using 2 moles of facilitating anions per mole of bretylium tosylate instead of equimolar amounts as in Example 13. The partition coefficient results obtained are set forth in Table 2A below:

TABLE 2A PARTITION NOMINAL pH FACILITATING ANION COEFFICIENT 0.8 di(2-ethylhexyl)sulfosuccinate 3.58 2.2 di(2-ethylhexyl)sulfosuccinate 4.98 5.6 di(2-ethylhexyl)sulfosuccinate 4.94 7.0 di(2-ethylhexyl)sulfosuccinate 5.03 0.8 salicylate 1.06 2.2 salicylate 1.52 5.5 salicylate 1.61 7.0 salicylate 2.36

These results indicate that increasing the molar ratio of facilitating anion to bretylium cation can materially increase the value of the partition coefficient.

Example 15 Effect of the Facilitating Anion on Bretylium Efficacy

The increase in efficacy and bioavailability of the bretylium cation afforded by the formulations of the present invention was tested by orally administering formulations containing bretylium cations and di(2-ethylhexylsulfosuccinate) anions to male beagle dogs weighing approximately 10 kg, and subsequently measuring the ventricular fibrillation threshold (VFT), effective ventricular refractory period (EVRP), and rate-corrected Q-T_(c) interval of the dogs.

A formulation was orally administered to each dog in 3 divided doses in capsule form (i.e., conventional gelatin capsule). Each capsule contained 120 mg of bretylium tosylate; 120 mg of sodium di(2-ethylhexylsulfosuccinate); and 300 mg of sodium bicarbonate. The 3 capsules were administered to each dog over a period of 8 hours to achieve a bretylium tosylate total loading dose of approximately 36 mg per kg of body weight. The second capsule was administered 4 hr after the first capsule, and the third capsule was administered 8 hr after the first capsule.

Ten hours after administration of the first capsule, each dog was anesthetized by injection with 300 mg/kg pentabarbital (animal hospital supply grade). Additional doses of pentabarbital were administered as needed when the dogs started to awaken. The heart of each dog was exposed via an intercoastal approach, and the pericardium was opened. Stimulating bipolar silver-silver-chloride electrodes embedded in epoxy and recording electrodes were sewn to the right ventricular surface of each dog. The femoral artery was canulated to measure blood pressure.

The ventricular fibrillation threshold, effective ventricular refractory period, and rate-corrected Q-T_(c) interval of each dog were measured at various times during the 10-hour interval after administration of the third capsule. Electrical ventricular fibrillation thresholds were determined using a Grass Instruments Company constant current unit to initiate a gated train of 60 Hertz impulses of 2 millisecond duration via the pair of stimulating electrodes sewn into the surface of the right ventricle. The current train began immediately after ventricular activation to cover the vulnerable period during which ventricular fibrillation can be electrically induced. The stimulus strength began at 2.5 mamp, and was increased in 2.5 mamp steps until sustained ventricular fibrillation was induced. The heart was then electrically defibrillated. Subsequently, at least 1 hr was allowed for recovery and drug actions to increase before the ventricular fibrillation threshold was measured again. After each ventricular fibrillation threshold, the effective ventricular refractory period was determined. The rate-corrected Q-T_(c) interval was measured from the electrocardiogram. Effective ventricular refractory period was determined by establishing the earliest time that a stimulus delivered after ventricular activation could elicit another contraction. Rate-corrected Q-T_(c) interval was measured from a high speed electrocardiographic trace.

The ventricular fibrillation threshold, effective ventricular refractory period, and rate-corrected Q-T_(c) interval values measured in the dogs are set forth in Table 3A:

TABLE 3A TIME RATE-COR- AFTER RECTED LAST Q-T_(c) DOSE VFT EVRP INTERVAL SUBJECT (hr) (mamp) (msec) (sec) Untreated Dog N/A  5.0 135 270  (Average Value) Dog 1: 2.75 >50 (50 milliamps 205 408¹ was the maximum available current) 5 42.5 223 388¹ 8 30¹  220 380¹ 10  24.5¹ 224 374¹ Dog 2: 2 >50    219 400  5 40¹  208 388¹ 10 25¹  224 374¹ ¹Easy to defibrillate with one low current shock

These results show an increase in ventricular fibrillation threshold for the dogs, and, therefore, confirm that the formulations of the present invention increase the bioavailability of orally administered bretylium tosylate. In fact, fibrillation of the heart of the dogs could not be induced until about 6 hr after administration of the third loading dose capsule. After about 6 hr, the heart could be fibrillated with a 50 mamp current train, but the heart spontaneously defibrillated either once the current train was terminated or after a single low current defibrillation shock was applied. The time interval over which the increase in ventricular fibrillation threshold, effective ventricular refractory period, and rate-corrected Q-T_(c) interval was observed further suggests that a once or twice-a-day dosage of the formulations can suffice after the therapeutic concentration has been taken up by the binding sites in the heart.

Example 16 Effect of Various Facilitating Anions on Bretylium Efficacy

The increase in efficacy and bioavailability of the bretylium cation afforded by the formulations of the present invention were further tested by orally administering either 1 or 2 doses of various bretylium-tosylate/facilitating-anion combinations (all containing roughly an equimolar amount of bretylium tosylate and the facilitating anion), and then measuring the ventricular fibrillation threshold of the dogs at various times following the oral administration.

Mongrel dogs of either sex and weighing from about 10 to about 40 kg were used. The dogs were anesthetized with isofluorine gas and respired with a Harvard respirator using room air. A catheter electrode was passed under fluoroscopic observation via the jugular vein into the apex of the right ventricle and screwed into place in the myocardium of the right ventricle.

The ventricular fibrillation threshold (VFT) was determined using a Grass Instruments Company constant current unit to initiate a gated train of 60 Hertz impulses of 1 millisecond duration. The current train began immediately after ventricular activation and was sustained long enough to cover the vulnerable period during which ventricular fibrillation can be electrically induced. The stimulus strength began at 5 milliamps, and was increased in 3-4 milliamp steps until sustained ventricular fibrillation was induced (or until the maximum current of 50 milliamps was applied).

After the control VFT and EVRP were measured, the compositions were orally administered in capsule form via a stomach tube. Here, the capsule was pushed by a rod into the stomach tube, and then washed into the stomach with 50 ml glucose delivered through the stomach tube. The VFT and EVRP were measured at various times following this administration. In some instances (i.e., Dogs 1, 3, & 4) a second oral dose was also given 12 hours after the first dose.

Table 4 shows the results (“BT” means bretylium tosylate, “NaS” means sodium salicylate, “NaLS” means sodium lauryl sulfate, “VFT” means ventricular fibrillation threshold, and “EVRP” means effective ventricular refractory period). See also FIGS. 8-10. The effects of the bretylium were observed within 10 minutes of oral administration of the compositions. In addition, within 30 minutes of oral administration, the ventricular fibrillation threshold generally increased significantly. And, in many instances, the subject dogs eventually could not be fibrillated at all, even at the maximum current of the generator (VFT values of greater than 50 milliamps in Table 4 represent instances where the subject could not be fibrillated at the maximum current (i.e., 50 milliamps) of the generator). This effect on the ventricular fibrillation threshold generally continued over the entire 29 hour measuring period, thus suggesting that one dosage per day of these compositions is sufficient.

TABLE 4 VFT After Drug Dose VFT EVRP Second Drug Dose (VFT (mamp); EVRP After Drug Dose Before Drug Before Drug (administered at 12 hr % increase in VFT; (EVRP (msec); Dose Dose First Drug Dose after first drug dose) time of measurement time of measurement Subject (mamp) (msec) (per kg dog) (per kg dog) after first drug dose) after first drug dose) Dog 1 27 101  15 mg BT 10 mg BT >50; >85%; 24 hr 195; 24 hr  10 mg NaLS  7 mg NaLS Dog 2 13 150  20 mg BT No Second Dose 26; 100%; 1.25 hr 130; 1 hr  14 mg NaLS Dog 3 5 105  15 mg BT  5 mg BT 19; 280%; 2 hr 125; 30 min  10 mg NaLS 10 mg NaLS 34; 580%; 24 & 25 hr 134; 1.4 hr 36; 620%; 25.5 hr 138; 2 hr 33; 560%; 26 hr 141; 3 hr 132; 24 hr 130; 25 hr 138; 25.5 hr 135; 26 hr Dog 4 19 98  15 mg BT  5 mg BT >50; >163%; 2 hr 104; 30 min  10 mg NaLS  5 mg NaLS 36; 89%; 24.5 hr 110; 1 hr >50; >163%; 26 & 27 hr 108; 1.5 hr 112; 2 hr 128; 24.5 hr 111; 26 hr 112; 27 hr Dog 5 16 96  15 mg BT No Second Dose >50; >213%; 2.3 & 24 hr 107; 40 min   6 mg NaS 101; 2.3 hr 118; 24 hr Dog 6 15 100  15 mg BT No Second Dose >50; >233%; 30 min. 124; 13 min   6 mg NaS & 24 hr 150; 24 hr Dog 7 27 115  15 mg BT No Second Dose >50; >85%; 10 min,1 hr, 125; 10 min 6.5 mg aspirin 2.5 hr, & 29 hr 132; 1 hr 140; 1.5 hr 131; 29 hr Dog 8 11 95  15 mg BT No Second Dose 48; 336%; 10 min 90; 3 min 6.5 mg aspirin >50; >355%; 15 min, 97; 5 min 23 hr, & 23.25 hr 97; 10 min 105; 15 min 113; 23 hr 116; 23.25 hr Dog 9 11 148  15 mg BT No Second Dose 23; 109%; 15 min 150; 15 min 6.5 mg aspirin 36; 228%; 30 min 138; 30 min 35; 218%; 1 hr 140; 1 hr Dog 10 12 145  15 mg BT No Second Dose 49; 308%; 1 hr 155; 1 hr 6.5 mg aspirin >50; >317%; 3 & 24 hr 155; 3 hr 126; 24 hr Dog 11 11 164  15 mg BT No Second Dose 12; 9%; 22 min 165; 22 min 6.5 mg aspirin >50; >355%; 2.25 & 205; 2.25 hr 25 hr 152; 25 hr Dog 12 25 102  15 mg BT No Second Dose >50; >100%; 40 min & 102; 40 min 6.5 mg aspirin 24.7 hr 107; 24.7 hr

Example 17 The Effect of the Compositions of This Invention on Atrial Fibrillation

The effect of the compositions of this invention on atrial fibrillation was observed using a mongrel dog weighing approximately 35 kg. Atrial fibrillation was initially induced by a stimulating bipolar electrode catheter (to position this catheter electrode, it was passed into the right atrium via the jugular vein under fluoroscopic observation and then screwed into place in the myocardium of the right atrium). This electrode catheter delivered stimulating shocks consisting of a train of square wave pulses of 1 msec duration at 60 Hz. Atrial fibrillation was induced at a current of 6 milliamps.

Defibrillation was first attempted using a single dose of bretylium tosylate (Arnar-Stone, McGaw Park, Ill.) administered intravenously (the dose corresponded to 15 mg of bretylium tosylate per kg of the recipient). No effect on atrial fibrillation was observed.

Subsequently, a composition containing bretylium tosylate and aspirin was administered intravenously into the jugular vein. This composition was prepared using a commercially available tablet containing aspirin. The aspirin tablet was dissolved in warm water and filtered through a fine surgical gauze pad (to remove the bulk of the binder in the tablet). The resulting aspirin filtrate was then combined with an approximately equimolar amount of bretylium tosylate dissolved in 5% dextrose in water. Approximately 20 ml of this aqueous solution was injected into jugular vein of the atrially fibrillating dog (this dose corresponded to roughly 15 mg of bretylium tosylate per kg of the recipient and 6.5 mg of aspirin per Kg recipient). FIG. 1 shows the electrocardiogram for the dog following this administration. As can be seen, the atrial fibrillation was eliminated within 50 seconds of the administration. And the fibrillation subsequently could not be re-induced even at the maximum generator current of 50 milliamp.

Example 18 Effect of β-Receptor Blocker on Bretylium Efficacy

The increase in efficacy of the bretylium cation afforded by administering the bretylium cation in combination with a β-receptor blocker was tested by administering via injection bretylium tosylate alone, various β-receptor blockers alone, and various combinations of bretylium tosylate and β-receptor blockers to dogs, and then measuring the ventricular fibrillation threshold of the dogs 1-5 hours after drug administration. Table 5 shows the results.

TABLE 5 Composition Administered (per kg of recipient dog) Mean % Increase in VFT 20 mg bretylium tosylate 100-200% (no standard no β-receptor blocker deviation calculated) 0.075 mg propranolol 110% ± 40%  no bretylium 0.05 mg propranolol 320% ± 180% 20 mg bretylium tosylate 0.075 mg propranolol 540% ± 360% 10 mg bretylium tosylate 0.25 mg propranolol 310% ± 70%  20 mg bretylium tosylate 0.05 mg atenolol 330% ± 210% no bretylium 0.025 to 0.1 mg atenolol 550% ± 430% 20 mg bretylium tosylate 0.05 mg metoprolol 96% ± 70% no bretylium 0.035 mg metoprolol 410% ± 180% 10 mg bretylium tosylate 0.05 mg metoprolol 410% ± 190% 10 mg bretylium tosylate 0.035 to 0.1 mg metoprolol 370% ± 200% 10 mg bretylium tosylate 25 to 300 μg esmolol no significant increase no bretylium 200 μg esmolol 380% ± 150% 10 mg bretylium tosylate 25 μg esmolol 290% ± 110% 10 mg bretylium tosylate 25 μg esmolol 350% ± 180% 20 mg bretylium tosylate 300 μg esmolol 300% ± 190% 10 mg bretylium tosylate

In another experiment, the effect of a β-receptor blocker on the timing and efficacy of the bretylium cation was observed:

Control #1: Administration of Bretylium Tosylate Alone

When bretylium tosylate alone was intravenously administered (using a dose of about 20 mg of bretylium tosylate per kg of canine recipient), a substantial increase in the ventricular fibrillation threshold began at 12-15 minutes after administration. About 3 hours after administration, this increase peaked at roughly 30 to 90 mamp, i.e., about 100 to 200% greater than the ventricular fibrillation threshold where no bretylium was administered at all (i.e., roughly 10 to 30 mamp).

Control #2: Administration of Propranolol Alone

When propranolol alone was intravenously administered (using a dose of 0.05 to 0.5 mg/kg), there was a 110%±40% increase in the ventricular fibrillation threshold.

Administration of Bretylium Tosylate and Propranolol

When a combination of bretylium tosylate and propranolol was intravenously administered (using a dose of 20 mg/kg bretylium tosylate and 0.05 to 0.2 mg/kg propranolol) to 10 dogs, the ventricular fibrillation threshold increased to greater than 100 mamp (the maximum current generator output) within 3 to 10 minutes of the administration, and the hearts of all 10 dogs remained non-fibrillatable for the entire 6 hour study period after the administration.

Example 19 Administration of Bretylium Lauryl Sulfate in Capsule Form

The effect of the compositions of this invention on atrial and ventricular fibrillation were observed using a mongrel dog weighing approximately 35 kg.

At time zero, a 5 milliamp stimulus was applied and a ventricular fibrillation threshold (VFT) was established. FIG. 2 shows an electrocardiogram of a dog chosen as a control having normal sinus rhythm. At 10 minutes, a 2 milliamp current was applied to attempt to establish atrial fibrillation, but it was unsuccessful. At 12.53 minutes, a dilute solution of aconitine was dabbed on the right surface of the atrium, which caused a brief burst of atrial tachycardia followed by sustained atrial fibrillation. FIG. 3 is an electrocardiogram of the dog taken immediately after the aconitine was painted on the atrium and FIG. 4 is an electrocardiogram of the dog showing sustained atrial fibrillation after a short burst of atrial tachycardia following the aconitine painting. The atrial fibrillation was sustained for a little over an hour as demonstrated in FIGS. 5 and 6.

At 1 hour and 20 minutes, the dog was given a 50 mg/kg dose of bretylium lauryl sulfate salt. Approximately 18 minutes after the dose (1 hour and 38 minutes into the experiment), periods of a normal sinus rhythm were observed as demonstrated in FIG. 7. Atrial fibrillation ceased entirely 19 minutes after the dose was applied (1 hour and 39 minutes into the experiment).

At three hours and twenty minutes, the dog's left anterior coronary artery was ligated to attempt to induce ventricular fibrillation by coronary occlusion. No ventricular fibrillation was observed. After three hours and thirty five minutes, the occlusion was released, and again, no ventricular fibrillation was observed for the following two minutes.

Next, at three hours and thirty-seven minutes, 50 milliamps (the maximum current) was applied in an attempt to induce ventricular fibrillation and/or atrial fibrillation. No fibrillation (atrial or ventricular) could be induced by electrical stimulation.

Thus, the current invention provides protection against coronary ligation and reperfusion, electrical fibrillation and chemical stimulation (aconitine).

Example 20 Method of Making Bretylium Dodecylsulfate

A concentrated aqueous solution of bretylium bromide may be prepared by treating 2-bromobenzyl bromide with ethyldimethylamine in the presence of aqueous sodium bicarbonate. The sodium salt of the hydrophobic or weakly hydrophilic anion is then added to the aqueous bretylium bromide solution, and then the required bretylium salt is extracted from the aqueous solution or else is dispersed with a suitable, water-insoluble solvent. The nonaqueous solution is dehydrated and solvent is evaporated under vacuum, leaving the nonvolatile, desired bretylium salt.

A. Preparation of Bretylium Bromide

25 g (0.1 moles) of 2-bromobenzyl bromide was added to 100 ml of distilled water in a 250 ml 3-necked round bottom flask, fitted with a pH probe (combined glass electrode and calomel reference electrode) a thermometer, and an addition funnel. A two phase mixture was obtained. To this mixture, 29.2 g (0.4 moles) of ethyldimethylamine were added in small portions. After each portion of amine was added, a small quantity of 10 M HCl was added, so as to maintain the pH at a value between 9 and 10. (Ethyldimethylamine has a pK of approximately 10. At a pH below 9, almost all of the amine would be protonated, slowing the reaction. At a pH above 10, the hydrolysis of 2-bromobenzyl bromide by hydroxide to 2-bromobenzyl alcohol is accelerated, without much acceleration of the product-forming reaction.)

Thirty-eight minutes after the addition was completed, the mixture became a homogeneous solution. Since 2-bromobenzyl bromide is almost completely water-insoluble, it was assumed that reaction was complete. (Ethyldimethylamine is water-soluble.) The total volume of the final solution was 130 ml, so the concentration of bretylium bromide was 0.77 upon full completion of the reaction. This solution may also contain some excess, unreacted ethyldimethylamine and some ethyldimethylammonium bromide.

B. Preparation of Bretylium Dodecylsulfate

Bretylium dodecylsulfate was prepared as an example of the preparation of bretylium salts of hydrophobic or weakly hydrophilic anions. A 25.5 g sample of the bretylium bromide solution prepared above was mixed under vacuum in a rotary evaporator, reducing its mass to 7.48 g by evaporation. The removed, volatile material was ethyldimethylamine and water. Bretylium bromide is nonvolatile. This material contains approximately 2.6 mmoles of bretylium bromide per gram, based on the original concentration. To 2.0 g of this material (5.2 mmoles of bretylium bromide) were added 2.0 g (6.2 mmoles) sodium dodecylsulfate, 2.0 g of distilled water, and 19 g of chloroform. A two phase mixture resulted. This was agitated vigorously, then allowed to separate. Previous distribution experiments suggested that bretylium dodecylsulfate would be concentrated in the chloroform phase, and sodium bromide in the aqueous phase. The chloroform was evaporated at about one torr; first, for 24 hours, at room temperature; then, at 43° C. for one hour. The residue was 1.7 g of very viscous, colorless, cloudy liquid (3.4 mmoles as bretylium dodecylsulfate, 65% yield).

To confirm the identity of the isolated material, its absorbance at 270 nm was compared with the known absorbance of the bretylium ion. The dodecylsulfate ion has no absorbance at this wavelength. 63 mg of product was dissolved in 10.28 g of distilled water and 1.0 g of this solution was diluted to 13.67 g with distilled water. If the product is bretylium dodecylsulfate this should give an 0.00088 M solution. Using the previously determined molar absorption coefficient for the bretylium ion, 350, an absorbance of 0.307 is predicted for this solution in a cell of 1.00 cm path length. The measured absorbance was 0.329. This agreement is considered a good confirmation of the identity of the material. The small excess of the measured absorbance over that calculated could be due to the presence of a small amount of absorbing impurity, or some combination of small experimental errors.

The isolated material was found to be an active antifibrilant when it was orally administered to a dog by the inventors.

Example 21 Effect of Administration of Bretylium Tosylate/Aspirin/Propranol on Ventricular Fibrillation Threshold

This example demonstrates the oral administration of a bretylium/aspirin/propranolol composition and the corresponding effect on ventricular fibrillation threshold (VFT) and effective ventricular refractory period (EVRP).

The experiment was conducted using a mongrel dog weighing approximately 23 kg. The dog was anesthetized with isofluorine gas and respired with a Harvard respirator using room air. The dog's chest was opened via a midsternotomy to expose the heart and an electrode was applied to the surface of the right ventricle.

The ventricular fibrillation threshold was determined using a Grass Instruments Company constant current unit to initiate a gated train of 60 Hz impulses of 1 millisecond duration. The current train began immediately after ventricular activation and was sustained long enough to cover the vulnerable period during which ventricular fibrillation can be electrically induced. The ventricular stimulus began at 3 milliamps and was increased in 3-4 milliamp steps until sustained ventricular fibrillation was induced (or until the maximum current of 50 milliamps was applied.)

After the control VFT and EVRP were measured, a combination comprising bretylium tosylate, the sodium salt of acetylsalicylic acid and propranolol was orally administered via a stomach tube. First, about 1 mg/kg of propranolol was pushed by a rod into the stomach tube and washed into the stomach with 500 mg of bicarbonate dissolved in 50 mL of water. Immediately following, 15 mg/kg of a composition in capsule form containing an equimolar amount of bretylium tosylate and the acetylsalicylic acid was pushed by a rod into the stomach tube and washed into the stomach with a liquid comprising sodium citrate, citric acid and aspirin in the form of a standard, commercially available Alka-Seltzer tablet dissolved in 50 mL of water. VFT and EVRP were then measured at various times following the administration. Heart rate and blood pressure were also measured throughout the experiment. Results of the VFT and EVRP measurements are shown in Table 6. Results of the heart rate and blood pressure measurements are shown in Table 7.

Generally, after 5 minutes, VFT almost doubled. After 30 minutes VFT was more than six times the control and VFT continued to increase progressively over time. After 120 minutes, the heart still could not be fibrillated at 50 milliamps (the generator maximum). Therefore, the dog's left anterior descending coronary artery was occluded to attempt to induce ventricular fibrillation. Generally, coronary occlusion significantly reduces VFT or causes spontaneous ventricular fibrillation. However, despite 20 minutes of LAD occlusion, the heart could still not be fibrillated at 50 milliamps. At 139 minutes, the occlusion was released, and again, no ventricular fibrillation or reperfusion ventricular fibrillation was observed for the following 30 minutes (VFT was greater than 50 milliamps).

As seen in Table 7, cardiac hemodynamics (blood pressure and heart rate) remained very stable throughout the procedure. Generally, blood pressure falls during coronary artery occlusion; but, the composition prevented a deleterious effect, and in fact, improved cardiac hemodynamics during the experiment.

TABLE 6 Time after administration (min) VFT (mamp) EVRP (msec) −20 6 105 0 Administration 5 11 108 30 37 110 60 45 110 90 47 112 120 >50 112 124 LAD Ligated 139 >50 112

TABLE 7 Time after Heart Rate Blood Pressure Administration (min) (beats per min) (Systolic/Diastolic) −20 100 136/98  0 100 136/98  5 100 150/98  30 100 150/100 60 92 175/100 90 95 175/102 120 97 175/105 124 98 175/108 139 98 170/100 146 95 155/105

Example 22 Preparation of a Bretylium/Propranolol Resuscitation Solution

This example demonstrates the preparation of a resuscitation solution comprising a bretylium ion, aspirin and a β-receptor blocker. Such resuscitation solutions are suitable for administration to a patient suffering ventricular fibrillation.

The solution is prepared by dissolving bretylium tosylate (15 mg/kg), acetylsalicylic acid (7.5 mg/kg), propranolol (0.5 mg/kg), meglumine (0.3 mmol/kg) and potassium gluconate (2 mmol/dose) in an aqueous solution of 5% glucose (70 mL). For producing a resuscitation solution suitable for administration to an average (70 kg) human, the solution contains bretylium tosylate (1.05 g), acetylsalicylic acid (525 mg), propranolol (35 mg), meglumine (4095 mg) and potassium gluconate (468 mg) in 70 mL of an aqueous solution of 5% glucose.

Example 23 Preparation of a Bretylium/Metoprolol Resuscitation Solution

This example demonstrates the preparation of a resuscitation solution comprising a bretylium ion, aspirin and a β-receptor blocker. Such resuscitation solutions are suitable for administration to a patient suffering ventricular fibrillation.

The solution is prepared by dissolving bretylium tosylate (15 mg/kg), acetylsalicylic acid (7.5 mg/kg), metoprolol (0.5 mg/kg), meglumine (0.3 mmol/kg) and potassium gluconate (2 mmol/dose) in an aqueous solution of 5% glucose (70 mL). For producing a resuscitation solution suitable for administration to an average (70 kg) human, the solution contains bretylium tosylate (1.05 g), acetylsalicylic acid (525 mg), metoprolol (35 mg), meglumine (4095 mg) and potassium gluconate (468 mg) in 70 mL of an aqueous solution of 5% glucose.

Example 24 Preparation of a Bretylium/Esmolol Resuscitation Solution

This example demonstrates the preparation of a resuscitation solution comprising a bretylium ion, aspirin and a β-receptor blocker. Such resuscitation solutions are suitable for administration to a patient suffering ventricular fibrillation.

The solution is prepared by dissolving bretylium tosylate (15 mg/kg), acetylsalicylic acid (7.5 mg/kg), esmolol (0.25 mg/kg), meglumine (0.3 mmol/kg) and potassium gluconate (2 mmol/dose) in an aqueous solution of 5% glucose (70 mL). For producing a resuscitation solution suitable for administration to an average (70 kg) human, the solution contains bretylium tosylate (1.05 g), acetylsalicylic acid (525 mg), esmolol (17.5 mg), meglumine (4095 mg) and potassium gluconate (468 mg) in 70 mL of an aqueous solution of 5% glucose.

Example 25 Preparation of a Bretylium/Propranolol Resuscitation Solution

This example demonstrates the preparation of a resuscitation solution comprising a bretylium ion, aspirin and a β-receptor blocker. Such resuscitation solutions are suitable for administration to a patient suffering ventricular fibrillation.

The solution is prepared by dissolving bretylium tosylate (15 mg/kg), acetylsalicylic acid (7.5 mg/kg), propranolol (0.5 mg/kg), meglumine (0.3 mmol/kg) and potassium gluconate (2 mmol/dose) in an aqueous solution of 5% glucose (70 mL). For producing a resuscitation solution suitable for administration to an average (70 kg) human, the solution contains bretylium tosylate (1.05 g), acetylsalicylic acid (525 mg), propranolol (35 mg), meglumine (4095 mg) and potassium gluconate (468 mg) in 70 mL of an aqueous solution of 5% glucose.

The above description of the preferred embodiments and the accompanying figures are intended only to acquaint others skilled in the art with the invention, its principles, and its practical application, so that others skilled in the art may adapt and apply the invention in its numerous forms, as may be best suited to the requirements of a particular use. The present invention, therefore, is not limited to the above embodiments, and may be variously modified.

All patent documents and other literature references cited in this specification are incorporated herein by reference measured in said subject prior to the administration of said pharmaceutical composition. 

1. A pharmaceutical combination useful for preventing and/or treating a cardiovascular condition, the pharmaceutical combination comprising: a bretylium cation or a source of a bretylium cation; an acetylsalicylate anion or a source of an acetylsalicylate anion; and a β-receptor blocker or a source of a β-receptor blocker, said acetylsalicylate anion comprising a compound of the structure:

wherein: R¹⁷ is independently hydrocarbyl or substituted hydrocarbyl; R¹⁸ is hydrogen, hydrocarbyl or substituted hydrocarbyl; and said bretylium cation or said source of a bretylium cation, said acetylsalicylate anion or source of an acetylsalicylate anion, and said β-receptor blocker or said source of a β-receptor blocker together are present in said pharmaceutical combination in a therapeutically effective amount.
 2. A pharmaceutical combination as set forth in claim 1 wherein said combination comprises a pharmaceutical composition comprising: a bretylium cation, an acetylsalicylate anion and a β-receptor blocker, said acetylsalicylate anion comprising a compound of the structure:

wherein: R¹⁷ is independently hydrocarbyl or substituted hydrocarbyl; R¹⁸ is hydrogen, hydrocarbyl or substituted hydrocarbyl; and said bretylium cation, said acetylsalicylate anion and said β-receptor blocker together are present in said pharmaceutical composition in a therapeutically effective amount.
 3. A pharmaceutical combination as set forth in claim 2 wherein the R¹⁷ substituent of the acetylsalicylate anion is hydrocarbyl and the R¹⁸ substituent of the acetylsalicylate anion is hydrogen.
 4. A pharmaceutical combination as set forth in claim 2 wherein the combination comprises a pharmaceutical composition having a molar ratio of acetylsalicylate anion to bretylium cation of from about 0.5 to about
 4. 5. A pharmaceutical combination as set forth in claim 4 wherein the combination comprises a pharmaceutical composition having a molar ratio of acetylsalicylate anion to bretylium cation of from about 1 to about
 2. 6. A pharmaceutical combination as set forth in claim 4 wherein the combination comprises a pharmaceutical composition having a molar ratio of acetylsalicylate anion to bretylium cation of from about 1.1 to about 1.5.
 7. A pharmaceutical combination as set forth in claim 2 wherein the combination comprises a pharmaceutical composition comprising a β-receptor blocker selected from the group consisting of propranolol, atenolol, esmolol, metoprolol, labetalol, talinolol, timolol, carvedilol and acebutolol.
 8. A pharmaceutical combination as set forth in claim 6, wherein said β-receptor blocker comprises propranolol.
 9. A pharmaceutical combination as set forth in claim 6, wherein said β-receptor blocker comprises metoprolol.
 10. A pharmaceutical combination as set forth in claim 6, wherein said combination comprises from about 0.01% to about 1.0% by weight β-receptor blocker.
 11. A pharmaceutical combination as set forth in claim 6, wherein said combination comprises a pharmaceutical composition comprising from about 10% to about 60% by weight bretylium cation, from about 5% to about 30% by weight acetylsalicylate anion, and from about 0.01% to about 1.0% by weight β-receptor blocker.
 12. A pharmaceutical combination as set forth in claim 2, wherein when said pharmaceutical composition is orally administered to a subject, the electrical ventricular fibrillation threshold measured in said subject about five minutes after the administration of said pharmaceutical composition is at least about 25% higher than the electrical ventricular fibrillation threshold measured in said subject prior to the administration of said pharmaceutical composition.
 13. A pharmaceutical combination as set forth in claim 12, wherein when said pharmaceutical composition is orally administered to a subject, the electrical ventricular fibrillation threshold measured in said subject about five minutes after the administration of said pharmaceutical composition is at least about 50% higher than the electrical ventricular fibrillation threshold measured in said subject prior to the administration of said pharmaceutical composition.
 14. A pharmaceutical combination as set forth in claim 12, wherein when said pharmaceutical composition is orally administered to a subject, the electrical ventricular fibrillation threshold measured in said subject about five minutes after the administration of said pharmaceutical composition is at least about 75% higher than the electrical ventricular fibrillation threshold measured in said subject prior to the administration of said pharmaceutical composition.
 15. A pharmaceutical combination as set forth in claim 2, wherein when said pharmaceutical composition is orally administered to a subject, the electrical ventricular fibrillation threshold measured in said subject about five minutes after the administration of said pharmaceutical composition is about two times higher than the electrical ventricular fibrillation threshold measured in said subject prior to the administration of said pharmaceutical composition.
 16. A pharmaceutical combination as set forth in claim 2, wherein when said pharmaceutical composition is orally administered to a subject, the electrical ventricular fibrillation threshold measured in said subject about 30 minutes after the administration of said pharmaceutical composition is at least about two times higher than the electrical ventricular fibrillation threshold measured in said subject before the administration of said pharmaceutical composition.
 17. A pharmaceutical combination as set forth in claim 2, wherein when said pharmaceutical composition is orally administered to a subject, the electrical ventricular fibrillation threshold measured in said subject about 30 minutes after the administration of said pharmaceutical composition is at least about four times higher than the electrical ventricular fibrillation threshold measured in said subject before the administration of said pharmaceutical composition.
 18. A pharmaceutical combination as set forth in claim 2, wherein when said pharmaceutical composition is orally administered to a subject, the electrical ventricular fibrillation threshold measured in said subject about 30 minutes after the administration of said pharmaceutical composition is about six times higher than the electrical ventricular fibrillation threshold measured in said subject before the administration of said pharmaceutical composition.
 19. A pharmaceutical combination as set forth in claim 2 further comprising an anti-hypotensive agent.
 20. A pharmaceutical combination as set forth in claim 19 wherein said anti-hypotensive agent comprises epinephrine.
 21. A pharmaceutical combination as set forth in claim 19 wherein said anti-hypotensive agent comprises a tricyclic anti-depressant compound.
 22. A pharmaceutical combination as set forth in claim 21 wherein said anti-hypotensive agent comprises a tricyclic anti-depressant compound selected from the group consisting of protriptyline, mazindol, amitriptyline, nortriptyline and desipramine.
 23. A pharmaceutical combination as set forth in claim 19, wherein said combination comprises a pharmaceutical composition comprising from about 0.01% to about 0.5% by weight anti-hypotensive agent.
 24. A pharmaceutical combination as set forth in claim 2 wherein said composition further comprises a neutralizing agent.
 25. A pharmaceutical combination as set forth in claim 24 wherein said neutralizing agent comprises a mono-, di-, or poly-amino sugar.
 26. A pharmaceutical combination as set forth in claim 25 wherein said neutralizing agent comprises methyl glucamine.
 27. A pharmaceutical combination as set forth in claim 24, wherein said combination comprises a pharmaceutical composition comprising from about 0.01% to about 70% by weight neutralizing agent.
 28. A pharmaceutical combination as set forth in claim 27, wherein said combination comprises a pharmaceutical composition comprising from about 30% to about 70% by weight neutralizing agent.
 29. A pharmaceutical combination as set forth in claim 2 wherein said composition further comprises a neutralizing agent and a buffering agent.
 30. A pharmaceutical combination as set forth in claim 29 wherein said neutralizing agent comprises sodium bicarbonate or sodium citrate and said buffering agent comprises citric acid.
 31. A pharmaceutical combination as set forth in claim 2 wherein the combination comprises a pharmaceutical composition suitable for oral administration.
 32. A pharmaceutical combination as set forth in claim 2, wherein said combination is in a form comprising a tablet or a capsule.
 33. A pharmaceutical combination as set forth in claim 2, wherein said combination is in a form comprising a solution or suspension.
 34. A pharmaceutical combination as set forth in claim 2, wherein said combination is in a form suitable for administering via injection.
 35. A pharmaceutical combination as set forth in claim 34, wherein said combination is suitable for intravenous or intramuscular injection.
 36. A pharmaceutical combination as set forth in claim 34, wherein said combination further comprises a buffer.
 37. A pharmaceutical combination as set forth in claim 34, wherein said combination further comprises a bulking, dispersing, wetting or suspending agent.
 38. A pharmaceutical combination as set forth in claim 34, wherein said combination further comprises eplerenone.
 39. A pharmaceutical combination as set forth in claim 1 wherein said combination comprises a pharmaceutical kit comprising: a source of a bretylium cation, a source of an acetylsalicylate anion and a source of a β-receptor blocker, said acetylsalicylate anion comprising a compound of the structure:

wherein: R¹⁷ is independently hydrocarbyl or substituted hydrocarbyl; R¹⁸ is hydrogen, hydrocarbyl or substituted hydrocarbyl; and said bretylium cation source, said acetylsalicylate anion source and said β-receptor blocker source together are present in said pharmaceutical kit in a therapeutically effective amount.
 40. A pharmaceutical combination as set forth in claim 39 wherein the R¹⁷ substituent of the acetylsalicylate anion is hydrocarbyl and the R¹⁸ substituent of the acetylsalicylate anion is hydrogen.
 41. A pharmaceutical combination as set forth in claim 39 wherein the molar ratio of said acetylsalicylate anion to said bretylium cation is from about 0.5 to about
 4. 42. A pharmaceutical combination as set forth in claim 41 wherein the molar ratio of said acetylsalicylate anion to said bretylium cation is from about 1 to about
 2. 43. A pharmaceutical combination as set forth in claim 41 wherein the molar ratio of said acetylsalicylate anion to said bretylium cation is from about 1.1 to about 1.5.
 44. A pharmaceutical combination as set forth in claim 39 wherein said β-receptor blocker is selected from the group consisting of propranolol, atenolol, esmolol, metoprolol, labetalol, talinolol, timolol, carvedilol and acebutolol.
 45. A pharmaceutical combination as set forth in claim 44, wherein said β-receptor blocker comprises propranolol.
 46. A pharmaceutical combination as set forth in claim 44, wherein said β-receptor blocker comprises metoprolol.
 47. A pharmaceutical combination as set forth in claim 39, wherein said combination comprises from about 0.01% to about 1.0% by weight β-receptor blocker.
 48. A pharmaceutical combination as set forth in claim 39, wherein when the components of said pharmaceutical kit are orally administered to a subject, the electrical ventricular fibrillation threshold measured in said subject about five minutes after the administration of the components of said pharmaceutical kit is at least about 25% higher than the electrical ventricular fibrillation threshold measured in said subject prior to the administration of the components of said pharmaceutical kit.
 49. A pharmaceutical combination as set forth in claim 48, wherein when the components of said pharmaceutical kit are orally administered to a subject, the electrical ventricular fibrillation threshold measured in said subject about five minutes after the administration of the components of said pharmaceutical kit is at least about 50% higher than the electrical ventricular fibrillation threshold measured in said subject prior to the administration of the components of said pharmaceutical kit.
 50. A pharmaceutical combination as set forth in claim 48, wherein when the components of said pharmaceutical kit are orally administered to a subject, the electrical ventricular fibrillation threshold measured in said subject about five minutes after the administration of the components of said pharmaceutical kit is at least about 75% higher than the electrical ventricular fibrillation threshold measured in said subject prior to the administration of the components of said pharmaceutical kit.
 51. A pharmaceutical combination as set forth in claim 39, wherein when the components of said pharmaceutical kit are orally administered to a subject, the electrical ventricular fibrillation threshold measured in said subject about five minutes after the administration of the components of said pharmaceutical kit is about two times higher than the electrical ventricular fibrillation threshold measured in said subject prior to the administration of the components of said pharmaceutical kit.
 52. A pharmaceutical combination as set forth in claim 39, wherein when the components of said pharmaceutical kit are orally administered to a subject, the electrical ventricular fibrillation threshold measured in said subject about 30 minutes after the administration of the components of said pharmaceutical kit is at least about two times higher than the electrical ventricular fibrillation threshold measured in said subject before the administration of the components of said pharmaceutical kit.
 53. A pharmaceutical combination as set forth in claim 39, wherein when the components of said pharmaceutical kit are orally administered to a subject, the electrical ventricular fibrillation threshold measured in said subject about 30 minutes after the administration of the components of said pharmaceutical kit is at least about four times higher than the electrical ventricular fibrillation threshold measured in said subject before the administration of the components of said pharmaceutical kit.
 54. A pharmaceutical combination as set forth in claim 39, wherein when the components of said pharmaceutical kit are orally administered to a subject, the electrical ventricular fibrillation threshold measured in said subject about 30 minutes after the administration of the components of said pharmaceutical kit is about six times higher than the electrical ventricular fibrillation threshold measured in said subject before the administration of the components of said pharmaceutical kit.
 55. A pharmaceutical combination as set forth in claim 39 further comprising a source of an anti-hypotensive agent.
 56. A pharmaceutical combination as set forth in claim 55 wherein said anti-hypotensive agent comprises epinephrine.
 57. A pharmaceutical combination as set forth in claim 55 wherein said anti-hypotensive agent comprises a tricyclic anti-depressant compound.
 58. A pharmaceutical combination as set forth in claim 57 wherein said anti-hypotensive agent comprises a tricyclic anti-depressant compound selected from the group consisting of protriptyline, mazindol, amitriptyline, nortriptyline and desipramine.
 59. A pharmaceutical combination as set forth in claim 55, wherein said combination comprises from about 0.01% to about 0.5% by weight anti-hypotensive agent.
 60. A pharmaceutical combination as set forth in claim 39 wherein said kit further comprises a source of a neutralizing agent.
 61. A pharmaceutical combination as set forth in claim 60 wherein said neutralizing agent comprises a mono-, di-, or poly-amino sugar.
 62. A pharmaceutical combination as set forth in claim 61 wherein said neutralizing agent comprises methyl glucamine.
 63. A pharmaceutical combination as set forth in claim 60, wherein said combination comprises from about 0.01% to about 70% by weight neutralizing agent.
 64. A pharmaceutical combination as set forth in claim 63, wherein said combination comprises from about 30% to about 70% by weight neutralizing agent.
 65. A pharmaceutical combination as set forth in claim 39 wherein said kit further comprises a source of a neutralizing agent and a source of a buffering agent.
 66. A pharmaceutical combination as set forth in claim 65 wherein said neutralizing agent comprises sodium bicarbonate or sodium citrate and said buffering agent comprises citric acid.
 67. A pharmaceutical combination as set forth in claim 66 wherein the source of said neutralizing agent and the source of said buffering agent are in combination and comprise a commercially available Alka Seltzer® tablet.
 68. A pharmaceutical combination as set forth in claim 39 wherein said combination comprises a pharmaceutical kit comprising at least 3 separate unit dosages, said unit dosages being a unit dosage comprising said source of said bretylium cation, a unit dosage comprising said source of said acetylsalicylate anion and a unit dosage comprising said source of said β-receptor blocker.
 69. A pharmaceutical combination as set forth in claim 39 wherein the source of said bretylium cation comprises bretylium tosylate.
 70. A pharmaceutical combination useful for preventing and/or treating a cardiovascular condition, said pharmaceutical combination comprising: a bretylium cation or a source of a bretylium cation; acetylsalicylic acid or an alkali metal salt of acetylsalicylic acid; and a β-receptor blocker or a source of a β-receptor blocker, wherein: said pharmaceutical combination is suitable for oral ingestion; and said bretylium cation or said source of a bretylium cation, said acetylsalicylic acid or said alkali metal salt of acetylsalicylic acid, and said β-receptor blocker or said source of a β-receptor blocker together are present in said pharmaceutical composition in a therapeutically effective amount.
 71. A pharmaceutical combination as set forth in claim 70 wherein the combination comprises a pharmaceutical composition comprising: a bretylium cation, acetylsalicylic acid or an alkali metal salt of acetylsalicylic acid and a β-receptor blocker, wherein: said pharmaceutical composition is suitable for oral ingestion; and said bretylium cation, said acetylsalicylic acid or alkali metal salt of acetylsalicylic acid and said β-receptor blocker together are present in said pharmaceutical composition in a therapeutically effective amount.
 72. A pharmaceutical combination as set forth in claim 71 wherein the molar ratio of said acetylsalicylic acid or alkali metal salt of acetylsalicylic acid to said bretylium cation is from about 0.5 to about
 4. 73. A pharmaceutical combination as set forth in claim 72 wherein the molar ratio of said acetylsalicylic acid or alkali metal salt of acetylsalicylic acid to said bretylium cation is from about 1 to about
 2. 74. A pharmaceutical combination as set forth in claim 72 wherein the molar ratio of said acetylsalicylic acid or alkali metal salt of acetylsalicylic acid to bretylium cation is from about 1.1 to about 1.5.
 75. A pharmaceutical combination as set forth in claim 71 wherein said β-receptor blocker is selected from the group consisting of propranolol, atenolol, esmolol, metoprolol, labetalol, talinolol, timolol, carvedilol and acebutolol.
 76. A pharmaceutical combination as set forth in claim 71, wherein said β-receptor blocker comprises propranolol.
 77. A pharmaceutical combination as set forth in claim 71, wherein said β-receptor blocker comprises metoprolol.
 78. A pharmaceutical combination as set forth in claim 71, wherein said combination comprises from about 0.01% to about 1.0% by weight β-receptor blocker.
 79. A pharmaceutical combination as set forth in claim 71, wherein said combination comprises a pharmaceutical composition comprising from about 10% to about 60% by weight bretylium cation, from about 5% to about 30% by weight acetylsalicylic acid or alkali metal salt of acetylsalicylic acid, and from about 0.01% to about 1.0% by weight β-receptor blocker.
 80. A pharmaceutical combination as set forth in claim 71, wherein when said pharmaceutical composition is orally administered to a subject, the electrical ventricular fibrillation threshold measured in said subject about five minutes after the administration of said pharmaceutical composition is at least about 25% higher than the electrical ventricular fibrillation threshold measured in said subject prior to the administration of said pharmaceutical composition.
 81. A pharmaceutical combination as set forth in claim 80, wherein when the pharmaceutical composition is orally administered to a subject, the electrical ventricular fibrillation threshold measured in said subject about five minutes after the administration of said pharmaceutical composition is at least about 50% higher than the electrical ventricular fibrillation threshold measured in said subject prior to the administration of said pharmaceutical composition.
 82. A pharmaceutical combination as set forth in claim 80, wherein when said pharmaceutical composition is orally administered to a subject, the electrical ventricular fibrillation threshold measured in said subject about five minutes after the administration of said pharmaceutical composition is at least about 75% higher than the electrical ventricular fibrillation threshold measured in said subject prior to the administration of said pharmaceutical composition.
 83. A pharmaceutical combination as set forth in claim 71, wherein when said pharmaceutical composition is orally administered to a subject, the electrical ventricular fibrillation threshold measured in said subject about five minutes after the administration of said pharmaceutical composition is about two times higher than the electrical ventricular fibrillation threshold measured in said subject prior to the administration of said pharmaceutical composition.
 84. A pharmaceutical combination as set forth in claim 71, wherein when said pharmaceutical composition is orally administered to a subject, the electrical ventricular fibrillation threshold measured in said subject about 30 minutes after the administration of said pharmaceutical composition is at least about two times higher than the electrical ventricular fibrillation threshold measured in said subject before the administration of said pharmaceutical composition.
 85. A pharmaceutical combination as set forth in claim 71, wherein when said pharmaceutical composition is orally administered to a subject, the electrical ventricular fibrillation threshold measured in said subject about 30 minutes after the administration of said pharmaceutical composition is at least about four times higher than the electrical ventricular fibrillation threshold measured in said subject before the administration of said pharmaceutical composition.
 86. A pharmaceutical combination as set forth in claim 71, wherein when said pharmaceutical composition is orally administered to a subject, the electrical ventricular fibrillation threshold measured in said subject about 30 minutes after the administration of said pharmaceutical composition is about six times higher than the electrical ventricular fibrillation threshold measured in said subject before the administration of said pharmaceutical composition.
 87. A pharmaceutical combination as set forth in claim 71 further comprising an anti-hypotensive agent.
 88. A pharmaceutical combination as set forth in claim 87 wherein said anti-hypotensive agent comprises epinephrine.
 89. A pharmaceutical combination as set forth in claim 87 wherein said anti-hypotensive agent comprises a tricyclic anti-depressant compound.
 90. A pharmaceutical combination as set forth in claim 89 wherein said anti-hypotensive agent comprises a tricyclic anti-depressant compound selected from the group consisting of protriptyline, mazindol, amitriptyline, nortriptyline and desipramine.
 91. A pharmaceutical combination as set forth in claim 87, wherein said combination comprises a pharmaceutical composition comprising from about 0.01% to about 0.5% by weight anti-hypotensive agent.
 92. A pharmaceutical combination as set forth in claim 71 wherein said composition further comprises a neutralizing agent.
 93. A pharmaceutical combination as set forth in claim 92 wherein said neutralizing agent comprises a mono-, di-, or poly-amino sugar.
 94. A pharmaceutical combination as set forth in claim 93 wherein said neutralizing agent comprises methyl glucamine.
 95. A pharmaceutical combination as set forth in claim 92, wherein said combination comprises a pharmaceutical composition comprising from about 0.01% to about 70% by weight neutralizing agent.
 96. A pharmaceutical combination as set forth in claim 95, wherein said combination comprises a pharmaceutical composition comprising from about 30% to about 70% by weight neutralizing agent.
 97. A pharmaceutical combination as set forth in claim 71 wherein said composition further comprises a neutralizing agent and a buffering agent.
 98. A pharmaceutical combination as set forth in claim 97 wherein said neutralizing agent comprises sodium bicarbonate or sodium citrate and said buffering agent comprises citric acid.
 99. A pharmaceutical combination as set forth in claim 71 wherein the combination comprises a pharmaceutical composition suitable for oral administration.
 100. A pharmaceutical combination as set forth in claim 71, wherein said combination is in a form comprising a tablet or a capsule.
 101. A pharmaceutical combination as set forth in claim 71, wherein said combination is in a form comprising a solution or suspension.
 102. A pharmaceutical combination as set forth in claim 71, wherein said combination is in a form suitable for administering via injection.
 103. A pharmaceutical combination as set forth in claim 102, wherein said combination is suitable for intravenous or intramuscular injection.
 104. A pharmaceutical combination as set forth in claim 102, wherein said combination further comprises a buffer.
 105. A pharmaceutical combination as set forth in claim 102, wherein said combination further comprises a bulking, dispersing, wetting or suspending agent.
 106. A pharmaceutical combination as set forth in claim 102, wherein said combination further comprises eplerenone.
 107. A pharmaceutical combination as set forth in claim 70 wherein said combination comprises a pharmaceutical kit comprising: a source of a bretylium cation, acetylsalicylic acid or an alkali metal salt of acetylsalicylic acid and a source of a β-receptor blocker, wherein: said source of said bretylium cation, said acetylsalicylic acid or alkali metal salt of acetylsalicylic acid, and said source of said β-receptor blocker are, in combination, suitable for oral ingestion; and said source of said bretylium cation, said acetylsalicylic acid or alkali metal salt of acetylsalicylic acid and said source of said β-receptor blocker are present in said kit in a therapeutically effective amount.
 108. A pharmaceutical combination as set forth in claim 107 wherein the molar ratio of said acetylsalicylic acid or alkali metal salt of acetylsalicylic acid to said bretylium cation is from about 0.5 to about
 4. 109. A pharmaceutical combination as set forth in claim 108 wherein the molar ratio of said acetylsalicylic acid or alkali metal salt of acetylsalicylic acid to said bretylium cation is from about 1 to about
 2. 110. A pharmaceutical combination as set forth in claim 108 wherein the molar ratio of acetylsalicylic acid or alkali metal salt of acetylsalicylic acid to bretylium cation is from about 1.1 to about 1.5.
 111. A pharmaceutical combination as set forth in claim 107 wherein said β-receptor blocker is selected from the group consisting of propranolol, atenolol, esmolol, metoprolol, labetalol, talinolol, timolol, carvedilol and acebutolol.
 112. A pharmaceutical combination as set forth in claim 111 wherein said β-receptor blocker comprises propranolol.
 113. A pharmaceutical combination as set forth in claim 111 wherein said β-receptor blocker comprises metoprolol.
 114. A pharmaceutical combination as set forth in claim 107, wherein said combination comprises from about 0.01% to about 1.0% by weight β-receptor blocker.
 115. A pharmaceutical combination as set forth in claim 107, wherein when the components of said pharmaceutical kit are orally administered to a subject, the electrical ventricular fibrillation threshold measured in said subject about five minutes after the administration of the components of said pharmaceutical kit is at least about 25% higher than the electrical ventricular fibrillation threshold measured in said subject prior to the administration of the components of said pharmaceutical kit.
 116. A pharmaceutical combination as set forth in claim 115, wherein when the components of said pharmaceutical kit are orally administered to a subject, the electrical ventricular fibrillation threshold measured in said subject about five minutes after the administration of the components of said pharmaceutical kit is at least about 50% higher than the electrical ventricular fibrillation threshold measured in said subject prior to the administration of the components of said pharmaceutical kit.
 117. A pharmaceutical combination as set forth in claim 115, wherein when the components of said pharmaceutical kit are orally administered to a subject, the electrical ventricular fibrillation threshold measured in said subject about five minutes after the administration of the components of said pharmaceutical kit is at least about 75% higher than the electrical ventricular fibrillation threshold measured in said subject prior to the administration of the components of said pharmaceutical kit.
 118. A pharmaceutical combination as set forth in claim 107, wherein when the components of said pharmaceutical kit are orally administered to a subject, the electrical ventricular fibrillation threshold measured in said subject about five minutes after the administration of the components of said pharmaceutical kit is about two times higher than the electrical ventricular fibrillation threshold measured in said subject prior to the administration of the components of said pharmaceutical kit.
 119. A pharmaceutical combination as set forth in claim 107, wherein when the components of said pharmaceutical kit are orally administered to a subject, the electrical ventricular fibrillation threshold measured in said subject about 30 minutes after the administration of the components of said pharmaceutical kit is at least about two times higher than the electrical ventricular fibrillation threshold measured in said subject before the administration of the components of said pharmaceutical kit.
 120. A pharmaceutical combination as set forth in claim 107, wherein when the components of said pharmaceutical kit are orally administered to a subject, the electrical ventricular fibrillation threshold measured in said subject about 30 minutes after the administration of the components of said pharmaceutical kit is at least about four times higher than the electrical ventricular fibrillation threshold measured in said subject before the administration of the components of said pharmaceutical kit.
 121. A pharmaceutical combination as set forth in claim 107, wherein when the components of said pharmaceutical kit are orally administered to a subject, the electrical ventricular fibrillation threshold measured in said subject about 30 minutes after the administration of the components of said pharmaceutical kit is about six times higher than the electrical ventricular fibrillation threshold measured in said subject before the administration of the components of said pharmaceutical kit.
 122. A pharmaceutical combination as set forth in claim 107 further comprising a source of an anti-hypotensive agent.
 123. A pharmaceutical combination as set forth in claim 122 wherein said anti-hypotensive agent comprises epinephrine.
 124. A pharmaceutical combination as set forth in claim 122 wherein said anti-hypotensive agent comprises a tricyclic anti-depressant compound.
 125. A pharmaceutical combination as set forth in claim 124 wherein said anti-hypotensive agent comprises a tricyclic anti-depressant compound selected from the group consisting of protriptyline, mazindol, amitriptyline, nortriptyline and desipramine.
 126. A pharmaceutical combination as set forth in claim 122, wherein said combination comprises from about 0.01% to about 0.5% by weight anti-hypotensive agent.
 127. A pharmaceutical combination as set forth in claim 107 wherein said pharmaceutical kit further comprises a source of a neutralizing agent.
 128. A pharmaceutical combination as set forth in claim 127 wherein said neutralizing agent comprises a mono-, di-, or poly-amino sugar.
 129. A pharmaceutical combination as set forth in claim 128 wherein said neutralizing agent comprises methyl glucamine.
 130. A pharmaceutical combination as set forth in claim 127, wherein said combination comprises from about 0.01% to about 70% by weight neutralizing agent.
 131. A pharmaceutical combination as set forth in claim 130, wherein said combination comprises from about 30% to about 70% by weight neutralizing agent.
 132. A pharmaceutical combination as set forth in claim 107 wherein said pharmaceutical kit further comprises a source of a neutralizing agent and a source of a buffering agent.
 133. A pharmaceutical combination as set forth in claim 132 wherein said neutralizing agent comprises sodium bicarbonate or sodium citrate and said buffering agent comprises citric acid.
 134. A pharmaceutical combination as set forth in claim 132 wherein the source of said neutralizing agent and the source of said buffering agent are in combination and comprise a commercially available Alka Seltzer® tablet.
 135. A pharmaceutical combination as set forth in claim 107, wherein said combination comprises at least 3 separate unit dosages, the unit dosages being a unit dosage comprising the source of said bretylium cation, a unit dosage comprising said acetylsalicylic acid or alkali metal salt of acetylsalicylic acid and a unit dosage comprising the source of said β-receptor blocker.
 136. A pharmaceutical combination as set forth in claim 107 wherein the source of said bretylium cation comprises bretylium tosylate.
 137. A pharmaceutical composition comprising from about 10% to about 40% by weight bretylium cation, from about 5% to about 40% by weight acetylsalicylate anion, and from about 0.1% to about 1.0% by weight β-receptor blocker.
 138. A pharmaceutical composition as set forth in claim 137, wherein said β-receptor blocker is selected from the group consisting of propranolol, atenolol, esmolol, metoprolol, labetalol, talinolol, timolol, carvedilol and acebutolol.
 139. A pharmaceutical composition as set forth in claim 138 wherein said β-receptor blocker comprises propranolol.
 140. A pharmaceutical composition as set forth in claim 138 wherein said β-receptor blocker comprises metoprolol.
 141. A pharmaceutical composition as set forth in claim 137 further comprising from about 30% to about 75% by weight neutralizing agent.
 142. A pharmaceutical composition as set forth in claim 141, wherein said neutralizing agent comprises a mono-, di-, or poly-amino sugar.
 143. A pharmaceutical composition as set forth in claim 142 wherein said neutralizing agent comprises methyl glucamine.
 144. A pharmaceutical composition comprising a bretylium cation, an acetylsalicylate anion, a β-receptor blocker and a neutralizing agent.
 145. A pharmaceutical composition as set forth in claim 144, wherein said β-receptor blocker is selected from the group consisting of propranolol, atenolol, esmolol, metoprolol, labetalol, talinolol, timolol, carvedilol and acebutolol.
 146. A pharmaceutical composition as set forth in claim 144 wherein said β-receptor blocker comprises propranolol.
 147. A pharmaceutical composition as set forth in claim 144 wherein said β-receptor blocker comprises metoprolol.
 148. A pharmaceutical composition as set forth in claim 145, wherein said neutralizing agent comprises a mono-, di-, or poly-amino sugar.
 149. A pharmaceutical composition as set forth in claim 148 wherein said neutralizing agent comprises methyl glucamine.
 150. A pharmaceutical composition as set forth in claim 144, wherein said composition is in a form comprising a solution or a suspension.
 151. A pharmaceutical composition as set forth in claim 150, wherein said composition is in a form suitable for administration as an emergency resuscitation solution for treating sudden cardiac arrest.
 152. A method for treating sudden cardiac arrest in a human or animal patient, the method comprising administering a pharmaceutical composition of claim 144 to a subject in need thereof.
 153. A method as set forth in claim 152, wherein said pharmaceutical composition comprises a bretylium cation, an acetylsalicylate anion, propranolol and methyl glucamine.
 154. A method as set forth in claim 152, wherein said pharmaceutical composition comprises a bretylium cation, an acetylsalicylate anion, metoprolol and methyl glucamine.
 155. A method for preventing and/or treating a cardiovascular condition, said method comprising orally administering a pharmaceutical combination of claim 1 to a subject in need thereof.
 156. A method as set forth in claim 155 wherein said pharmaceutical combination comprises a pharmaceutical composition comprising: a bretylium cation, an acetylsalicylate anion and a β-receptor blocker, said acetylsalicylate anion comprising a compound of the structure:

wherein: R¹⁷ is independently hydrocarbyl or substituted hydrocarbyl; R¹⁸ is hydrogen, hydrocarbyl or substituted hydrocarbyl; and said bretylium cation, said acetylsalicylate anion and said β-receptor blocker together are present in said pharmaceutical composition in a therapeutically effective amount.
 157. A method as set forth in claim 155, wherein said pharmaceutical combination comprises a pharmaceutical kit and said method comprises administering the components of said pharmaceutical kit to a subject in need thereof, said pharmaceutical kit comprising: a source of a bretylium cation, a source of an acetylsalicylate anion and a source of a β-receptor blocker, said acetylsalicylate anion comprising a compound of the structure:

wherein: R¹⁷ is independently hydrocarbyl or substituted hydrocarbyl; R¹⁸ is hydrogen, hydrocarbyl or substituted hydrocarbyl; and said bretylium cation source, said acetylsalicylate anion source and said β-receptor blocker source together are present in said pharmaceutical kit in a therapeutically effective amount.
 158. A method as set forth in claim 155, wherein said pharmaceutical combination is administered to: (1) prevent sudden cardiac death; (2) prevent and/or treat myocardial infarction; (3) prevent and/or treat congestive heart failure; (4) prevent and/or treat ventricular fibrillation; (5) prevent and/or treat ventricular arrhythmia; (6) prevent and/or treat ventricular tachycardia; (7) prevent and/or treat ventricular premature heartbeats; (8) prevent and/or treat atrioventricular dissociation; (9) prevent and/or treat multifocal ectopic beats; (10) prevent and/or treat premature ventricular extrasystoles; (11) prevent and/or treat bigeminal rhythm; (12) prevent and/or treat trigeminal rhythm; (13) prevent and/or treat angina pectoris; (14) prevent and/or treat coronary insufficiency; (15) prevent and/or treat sympathetically induced pain; (16) restore and/or maintain normal sinus rhythm; (17) increase the effective ventricular refractory period; (18) increase the sinus automaticity transiently; (19) prolong the Purkinje action potential duration; (20) induce post-ganglionic sympathetic blockade; (21) block the sympathetic nervous system; (22) reduce vascular impedance; (23) increase the electrical ventricular fibrillation threshold; (24) prolong the action potential duration of cardiac cells; and/or (25) prevent or treat congestive heart failure or coronary spasm.
 159. A method as set forth in claim 155 wherein said pharmaceutical combination is administered to prevent and/or treat atrial arrhythmia.
 160. A method as set forth in claim 155, wherein said pharmaceutical combination is administered to prevent and/or treat atrial fibrillation.
 161. A method as set forth in claim 160 wherein said combination is administered prior to the application of an external anti-defibrillatory shock.
 162. A method as set forth in claim 155 wherein said pharmaceutical combination is administered to prevent and/or treat atrial tachycardia.
 163. A method as set forth in claim 155 wherein said pharmaceutical combination is administered to a human.
 164. A method for preventing and/or treating a cardiovascular condition, said method comprising orally administering a pharmaceutical combination of claim 70 to a subject in need thereof.
 165. A method as set forth in claim 164, wherein the pharmaceutical combination comprises a pharmaceutical composition comprising: a bretylium cation, acetylsalicylic acid or an alkali metal salt of acetylsalicylic acid and a β-receptor blocker, wherein: said pharmaceutical composition is suitable for oral ingestion; and said bretylium cation, said acetylsalicylic acid or alkali metal salt of acetylsalicylic acid and said β-receptor blocker together are present in said pharmaceutical composition in a therapeutically effective amount.
 166. A method as set forth in claim 164, wherein said pharmaceutical combination comprises a pharmaceutical kit comprising: a source of a bretylium cation, acetylsalicylic acid or an alkali metal salt of acetylsalicylic acid and a source of a β-receptor blocker, wherein: said source of said bretylium cation, said acetylsalicylic acid or alkali metal salt of acetylsalicylic acid, and said source of said β-receptor blocker are, in combination, suitable for oral ingestion; and said source of said bretylium cation, said acetylsalicylic acid or alkali metal salt of acetylsalicylic acid and said source of said β-receptor blocker are present in said kit in a therapeutically effective amount.
 167. A method as set forth in claim 164, wherein said pharmaceutical combination is administered to: (1) prevent sudden cardiac death; (2) prevent and/or treat myocardial infarction; (3) prevent and/or treat congestive heart failure; (4) prevent and/or treat ventricular fibrillation; (5) prevent and/or treat ventricular arrhythmia; (6) prevent and/or treat ventricular tachycardia; (7) prevent and/or treat ventricular premature heartbeats; (8) prevent and/or treat atrioventricular dissociation; (9) prevent and/or treat multifocal ectopic beats; (10) prevent and/or treat premature ventricular extrasystoles; (11) prevent and/or treat bigeminal rhythm; (12) prevent and/or treat trigeminal rhythm; (13) prevent and/or treat angina pectoris; (14) prevent and/or treat coronary insufficiency; (15) prevent and/or treat sympathetically induced pain; (16) restore and/or maintain normal sinus rhythm; (17) increase the effective ventricular refractory period; (18) increase the sinus automaticity transiently; (19) prolong the Purkinje action potential duration; (20) induce post-ganglionic sympathetic blockade; (21) block the sympathetic nervous system; (22) reduce vascular impedance; (23) increase the electrical ventricular fibrillation threshold; (24) prolong the action potential duration of cardiac cells; and/or (25) prevent or treat congestive heart failure or coronary spasm.
 168. A method as set forth in claim 164 wherein said pharmaceutical combination is administered to prevent and/or treat atrial arrhythmia.
 169. A method as set forth in claim 164, wherein said pharmaceutical combination is administered to prevent and/or treat atrial fibrillation.
 170. A method as set forth in claim 169 wherein said combination is administered prior to the application of an external anti-defibrillatory shock.
 171. A method as set forth in claim 164 wherein said pharmaceutical combination is administered to prevent and/or treat atrial tachycardia.
 172. A method as set forth in claim 164 wherein said pharmaceutical combination is administered to a human.
 173. A method for preventing and/or treating a cardiovascular condition, said method comprising orally administering a pharmaceutical composition of claim 137 to a subject in need thereof.
 174. A method as set forth in claim 173, wherein said pharmaceutical composition is administered to: (1) prevent sudden cardiac death; (2) prevent and/or treat myocardial infarction; (3) prevent and/or treat congestive heart failure; (4) prevent and/or treat ventricular fibrillation; (5) prevent and/or treat ventricular arrhythmia; (6) prevent and/or treat ventricular tachycardia; (7) prevent and/or treat ventricular premature heartbeats; (8) prevent and/or treat atrioventricular dissociation; (9) prevent and/or treat multifocal ectopic beats; (10) prevent and/or treat premature ventricular extrasystoles; (11) prevent and/or treat bigeminal rhythm; (12) prevent and/or treat trigeminal rhythm; (13) prevent and/or treat angina pectoris; (14) prevent and/or treat coronary insufficiency; (15) prevent and/or treat sympathetically induced pain; (16) restore and/or maintain normal sinus rhythm; (17) increase the effective ventricular refractory period; (18) increase the sinus automaticity transiently; (19) prolong the Purkinje action potential duration; (20) induce post-ganglionic sympathetic blockade; (21) block the sympathetic nervous system; (22) reduce vascular impedance; (23) increase the electrical ventricular fibrillation threshold; (24) prolong the action potential duration of cardiac cells; and/or (25) prevent or treat congestive heart failure or coronary spasm.
 175. A method as set forth in claim 173 wherein said pharmaceutical combination is administered to prevent and/or treat atrial arrhythmia.
 176. A method as set forth in claim 175, wherein said pharmaceutical combination is administered to prevent and/or treat atrial fibrillation.
 177. A method as set forth in claim 176 wherein said combination is administered prior to the application of an external anti-defibrillatory shock.
 178. A method as set forth in claim 173 wherein said combination is administered prior to thrombolitic therapy.
 179. A method as set forth in claim 173 wherein said pharmaceutical combination is administered to prevent and/or treat atrial tachycardia.
 180. A method as set forth in claim 173 wherein said pharmaceutical combination is administered to treat acute myocardial infarction.
 181. A method as set forth in claim 173 wherein said pharmaceutical combination is administered to a human.
 182. A pharmaceutical combination as set forth in claim 1, wherein said combination further comprises bethanidine sulfate.
 183. A method for treating angina pectoris in a human or animal patient, said method comprising administering a pharmaceutical combination of claim 182 to a subject in need thereof.
 184. A method for treating and/or preventing shock, the method comprising administering a pharmaceutical combination comprising a bretylium cation or a source of a bretylium cation, a facilitating anion or a source of a facilitating anion, and an anti-hypotensive agent and/or a β-receptor blocker or a source of an anti-hypotensive agent and/or a β-receptor blocker to a human or animal patient in need thereof, wherein: said facilitating anion is less hydrophilic than a tosylate anion; and said bretylium cation or said source of a bretylium cation, said facilitating anion or said source of a facilitating anion, and said anti-hypotensive agent and/or said β-receptor blocker or said source of an anti-hypotensive agent and/or a β-receptor blocker together are present in said pharmaceutical combination in a therapeutically effective amount.
 185. A method as set forth in claim 184 wherein said pharmaceutical combination is administered for the treatment and/or prevention of septic shock, hemorrhagic shock, cardiogenic shock or hypovolemic shock. 